refactor: Index notation
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jstoobysmith
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6 changed files with 877 additions and 796 deletions
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@ -73,7 +73,10 @@ import HepLean.SpaceTime.LorentzGroup.Rotations
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import HepLean.SpaceTime.LorentzTensor.Basic
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import HepLean.SpaceTime.LorentzTensor.Contraction
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import HepLean.SpaceTime.LorentzTensor.Fin
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import HepLean.SpaceTime.LorentzTensor.IndexNotation
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import HepLean.SpaceTime.LorentzTensor.IndexNotation.Basic
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import HepLean.SpaceTime.LorentzTensor.IndexNotation.IndexListColor
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import HepLean.SpaceTime.LorentzTensor.IndexNotation.IndexString
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import HepLean.SpaceTime.LorentzTensor.IndexNotation.TensorIndex
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import HepLean.SpaceTime.LorentzTensor.MulActionTensor
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import HepLean.SpaceTime.LorentzTensor.Real.Basic
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import HepLean.SpaceTime.LorentzTensor.RisingLowering
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@ -1,795 +0,0 @@
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/-
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Copyright (c) 2024 Joseph Tooby-Smith. All rights reserved.
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Released under Apache 2.0 license as described in the file LICENSE.
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Authors: Joseph Tooby-Smith
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-/
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import HepLean.SpaceTime.LorentzTensor.Real.Basic
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import Init.NotationExtra
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/-!
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# Notation for Lorentz Tensors
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This file is currently a stub.
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We plan to set up index-notation for dealing with tensors.
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Some examples:
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- `ψᵘ¹ᵘ²φᵤ₁` should correspond to the contraction of the first index of `ψ` and the
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only index of `φ`.
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- `ψᵘ¹ᵘ² = ψᵘ²ᵘ¹` should define the symmetry of `ψ` under the exchange of its indices.
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- `θᵤ₂(ψᵘ¹ᵘ²φᵤ₁) = (θᵤ₂ψᵘ¹ᵘ²)φᵤ₁` should correspond to an associativity properity of
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contraction.
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It should also be possible to define this generically for any `LorentzTensorStructure`.
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Further we plan to make easy to define tensors with indices. E.g. `(ψ : Tenᵘ¹ᵘ²ᵤ₃)`
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should correspond to a (real Lorentz) tensors with 3 indices, two upper and one lower.
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For `(ψ : Tenᵘ¹ᵘ²ᵤ₃)`, if one writes e.g. `ψᵤ₁ᵘ²ᵤ₃`, this should correspond to a
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lowering of the first index of `ψ`.
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Further, it will be nice if we can have implicit contractions of indices
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e.g. in Weyl fermions.
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-/
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open Lean
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open Lean
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open Lean.Parser
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open Lean.Elab
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open Lean.Elab.Command
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variable {R : Type} [CommSemiring R]
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/-- The class defining index notation on a type `X`.
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Normally `X` will be taken as the type of colors of a `TensorStructure`. -/
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class IndexNotation (X : Type) where
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/-- The list of characters describing the index notation e.g.
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`{'ᵘ', 'ᵤ'}` for real tensors. -/
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charList : Finset Char
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/-- An equivalence between `X` (colors of indices) and `charList`.
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This takes every color of index to its notation character. -/
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notaEquiv : X ≃ charList
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namespace IndexNotation
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variable (X : Type) [IndexNotation X]
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variable [Fintype X] [DecidableEq X]
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/-- The map taking a color to its notation character. -/
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def nota {X : Type} [IndexNotation X] (x : X) : Char :=
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(IndexNotation.notaEquiv).toFun x
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/-- A character is a `notation character` if it is in `charList`. -/
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def isNotationChar (c : Char) : Bool :=
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if c ∈ charList X then true else false
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/-- A character is a numeric superscript if it is e.g. `⁰`, `¹`, etc. -/
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def isNumericSupscript (c : Char) : Bool :=
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c = '¹' ∨ c = '²' ∨ c = '³' ∨ c = '⁴' ∨ c = '⁵' ∨ c = '⁶' ∨ c = '⁷' ∨ c = '⁸' ∨ c = '⁹' ∨ c = '⁰'
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/-- Given a character `f` which is a notation character, this is true if `c`
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is a subscript when `f` is a subscript or `c` is a superscript when `f` is a
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superscript. -/
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def IsIndexId (f : Char) (c : Char) : Bool :=
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(isSubScriptAlnum f ∧ isNumericSubscript c) ∨
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(¬ isSubScriptAlnum f ∧ isNumericSupscript c)
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open String
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/-!
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## Lists of characters corresponding to indices.
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-/
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/-- The proposition for a list of characters to be the tail of an index
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e.g. `['¹', '⁷', ...]` -/
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def listCharIndexTail (f : Char) (l : List Char) : Prop :=
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l ≠ [] ∧ List.all l (fun c => IsIndexId f c)
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instance : Decidable (listCharIndexTail f l) := instDecidableAnd
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/-- The proposition for a list of characters to be the characters of an index
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e.g. `['ᵘ', '¹', '⁷', ...]` -/
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def listCharIndex (l : List Char) : Prop :=
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if h : l = [] then True
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else
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let sfst := l.head h
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if ¬ isNotationChar X sfst then False
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else
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listCharIndexTail sfst l.tail
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lemma listCharIndex_iff (l : List Char) : listCharIndex X l
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↔ (if h : l = [] then True else
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let sfst := l.head h
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if ¬ isNotationChar X sfst then False
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else listCharIndexTail sfst l.tail) := by
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rw [listCharIndex]
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instance : Decidable (listCharIndex X l) :=
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@decidable_of_decidable_of_iff _ _
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(@instDecidableDite _ _ _ _ _ <|
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fun _ => @instDecidableDite _ _ _ _ _ <|
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fun _ => instDecidableListCharIndexTail)
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(listCharIndex_iff X l).symm
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lemma dropWhile_isIndexSpecifier_length_lt (l : List Char) (hl : l ≠ []) :
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(List.dropWhile (fun c => !isNotationChar X c) l.tail).length < l.length := by
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let ld := l.tail.dropWhile (fun c => ¬ isNotationChar X c)
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let lt := l.tail.takeWhile (fun c => ¬ isNotationChar X c)
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simp only [gt_iff_lt]
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rename_i _ inst_1 _ _
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have h2 : lt ++ ld = l.tail := by
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exact List.takeWhile_append_dropWhile _ _
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have h3 := congrArg List.length h2
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rw [List.length_append] at h3
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have h4 : l.length ≠ 0 := by
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simp_all only [ne_eq, Bool.not_eq_true, Bool.decide_eq_false, List.takeWhile_append_dropWhile,
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List.length_tail, List.length_eq_zero, not_false_eq_true]
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have h5 : l.tail.length < l.length := by
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rw [List.length_tail]
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omega
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have h6 : ld.length < l.length := by
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omega
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simpa [ld] using h6
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/-- The proposition for a list of characters to be an index string. -/
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def listCharIndexString (l : List Char) : Prop :=
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if h : l = [] then True
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else
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let sfst := l.head h
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if ¬ isNotationChar X sfst then False
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else
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let lt := l.tail.takeWhile (fun c => ¬ isNotationChar X c)
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let ld := l.tail.dropWhile (fun c => ¬ isNotationChar X c)
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if ¬ listCharIndexTail sfst lt then False
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else listCharIndexString ld
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termination_by l.length
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decreasing_by
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simpa [ld, InvImage] using dropWhile_isIndexSpecifier_length_lt X l h
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/-- A bool version of `listCharIndexString` for computation. -/
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def listCharIndexStringBool (l : List Char) : Bool :=
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if h : l = [] then true
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else
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let sfst := l.head h
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if ¬ isNotationChar X sfst then false
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else
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let lt := l.tail.takeWhile (fun c => ¬ isNotationChar X c)
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let ld := l.tail.dropWhile (fun c => ¬ isNotationChar X c)
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if ¬ listCharIndexTail sfst lt then false
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else listCharIndexStringBool ld
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termination_by l.length
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decreasing_by
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simpa [ld, InvImage] using dropWhile_isIndexSpecifier_length_lt X l h
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lemma listCharIndexString_iff (l : List Char) : listCharIndexString X l
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↔ (if h : l = [] then True else
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let sfst := l.head h
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if ¬ isNotationChar X sfst then False
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else
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let lt := l.tail.takeWhile (fun c => ¬ isNotationChar X c)
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let ld := l.tail.dropWhile (fun c => ¬ isNotationChar X c)
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if ¬ listCharIndexTail sfst lt then False
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else listCharIndexString X ld) := by
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rw [listCharIndexString]
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lemma listCharIndexString_iff_bool (l : List Char) :
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listCharIndexString X l ↔ listCharIndexStringBool X l = true := by
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rw [listCharIndexString, listCharIndexStringBool]
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by_cases h : l = []
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simp [h]
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simp [h]
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intro _ _
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exact listCharIndexString_iff_bool _
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termination_by l.length
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decreasing_by
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simpa [InvImage] using dropWhile_isIndexSpecifier_length_lt X l h
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instance : Decidable (listCharIndexString X l) :=
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@decidable_of_decidable_of_iff _ _
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((listCharIndexStringBool X l).decEq true)
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(listCharIndexString_iff_bool X l).symm
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/-- If a list of characters corresponds to an index string, then its head is an
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index specifier. -/
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lemma listCharIndexString_head_isIndexSpecifier (l : List Char) (h : listCharIndexString X l)
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(hl : l ≠ []) : isNotationChar X (l.head hl) := by
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by_contra
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rw [listCharIndexString] at h
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simp_all only [↓reduceDIte, Bool.false_eq_true, not_false_eq_true, ↓reduceIte]
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/-- The tail of the first index in a list of characters corresponds to an index string
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(junk on other lists). -/
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def listCharIndexStringHeadIndexTail (l : List Char) : List Char :=
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l.tail.takeWhile (fun c => ¬ isNotationChar X c)
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/-- The tail of the first index in a list of characters corresponds to an index string
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is the tail of a list of characters corresponding to an index specified by the head. -/
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lemma listCharIndexStringHeadIndexTail_listCharIndexTail (l : List Char)
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(h : listCharIndexString X l) (hl : l ≠ []) :
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listCharIndexTail (l.head hl) (listCharIndexStringHeadIndexTail X l) := by
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by_contra
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have h1 := listCharIndexString_head_isIndexSpecifier X l h hl
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rw [listCharIndexString] at h
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rename_i _ _ _ _ x
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simp_all only [not_true_eq_false, Bool.not_eq_true, Bool.decide_eq_false, ite_not, if_false_right,
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ite_false, dite_false]
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obtain ⟨left, _⟩ := h
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simp [listCharIndexStringHeadIndexTail] at x
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simp_all only [Bool.false_eq_true]
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/-- The first list of characters which form a index, from a list of characters
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which form a string of indices. -/
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def listCharIndexStringHeadIndex (l : List Char) : List Char :=
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if h : l = [] then []
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else l.head h :: listCharIndexStringHeadIndexTail X l
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/-- The list of characters obtained by dropping the first block which
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corresponds to an index. -/
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def listCharIndexStringDropHeadIndex (l : List Char) : List Char :=
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l.tail.dropWhile (fun c => ¬ isNotationChar X c)
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lemma listCharIndexStringHeadIndex_listCharIndex (l : List Char) (h : listCharIndexString X l) :
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listCharIndex X (listCharIndexStringHeadIndex X l) := by
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by_cases h1 : l = []
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· subst h1
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simp [listCharIndex, listCharIndexStringHeadIndex]
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· simp [listCharIndexStringHeadIndex, listCharIndex, h1]
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apply And.intro
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exact listCharIndexString_head_isIndexSpecifier X l h h1
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exact listCharIndexStringHeadIndexTail_listCharIndexTail X l h h1
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lemma listCharIndexStringDropHeadIndex_listCharIndexString (l : List Char)
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(h : listCharIndexString X l) :
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listCharIndexString X (listCharIndexStringDropHeadIndex X l) := by
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by_cases h1 : l = []
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· subst h1
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simp [listCharIndexStringDropHeadIndex, listCharIndexString]
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· simp [listCharIndexStringDropHeadIndex, h1]
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rw [listCharIndexString] at h
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rename_i _ inst_1 _ _
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simp_all only [↓reduceDIte, Bool.not_eq_true, Bool.decide_eq_false, ite_not, if_false_right,
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if_false_left, Bool.not_eq_false]
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/-- Given a list list of characters corresponding to an index string, the list
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of lists of characters which correspond to an index and are non-zero corresponding
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to that index string. -/
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def listCharIndexStringTolistCharIndex (l : List Char) (h : listCharIndexString X l) :
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List ({lI : List Char // listCharIndex X lI ∧ lI ≠ []}) :=
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if hl : l = [] then [] else
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⟨listCharIndexStringHeadIndex X l, by
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apply And.intro (listCharIndexStringHeadIndex_listCharIndex X l h)
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simp [listCharIndexStringHeadIndex]
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exact hl⟩ ::
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(listCharIndexStringTolistCharIndex (listCharIndexStringDropHeadIndex X l)
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(listCharIndexStringDropHeadIndex_listCharIndexString X l h))
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termination_by l.length
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decreasing_by
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rename_i h1
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simpa [InvImage, listCharIndexStringDropHeadIndex] using
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dropWhile_isIndexSpecifier_length_lt X l hl
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/-!
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## Index and index strings
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-/
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/-- An index is a non-empty string satisfying the condtion `listCharIndex`,
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e.g. `ᵘ¹²` or `ᵤ₄₃` etc. -/
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def Index : Type := {s : String // listCharIndex X s.toList ∧ s.toList ≠ []}
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namespace Index
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variable {X : Type} [IndexNotation X] [Fintype X] [DecidableEq X]
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/-- Creats an index from a non-empty list of characters satisfying `listCharIndex`. -/
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def ofCharList (l : List Char) (h : listCharIndex X l ∧ l ≠ []) : Index X := ⟨l.asString, h⟩
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instance : ToString (Index X) := ⟨fun i => i.val⟩
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/-- Gets the first character in an index e.g. `ᵘ` as an element of `charList X`. -/
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def head (s : Index X) : charList X :=
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⟨s.val.toList.head (s.prop.2), by
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have h := s.prop.1
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have h2 := s.prop.2
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simp [listCharIndex] at h
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simp_all only [toList, ne_eq, Bool.not_eq_true, ↓reduceDIte]
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simpa [isNotationChar] using h.1⟩
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/-- The color associated to an index. -/
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def toColor (s : Index X) : X := (IndexNotation.notaEquiv).invFun s.head
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/-- A map from super and subscript numerical characters to the natural numbers,
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returning `0` on all other characters. -/
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def charToNat (c : Char) : Nat :=
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match c with
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| '₀' => 0
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| '₁' => 1
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| '₂' => 2
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| '₃' => 3
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| '₄' => 4
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| '₅' => 5
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| '₆' => 6
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| '₇' => 7
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| '₈' => 8
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| '₉' => 9
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| '⁰' => 0
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| '¹' => 1
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| '²' => 2
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| '³' => 3
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| '⁴' => 4
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| '⁵' => 5
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| '⁶' => 6
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| '⁷' => 7
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| '⁸' => 8
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| '⁹' => 9
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| _ => 0
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/-- The numerical characters associated with an index. -/
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def tail (s : Index X) : List Char := s.val.toList.tail
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/-- The natural numbers assocaited with an index. -/
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def tailNat (s : Index X) : List Nat := s.tail.map charToNat
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/-- The id of an index, as a natural number. -/
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def id (s : Index X) : Nat := s.tailNat.foldl (fun a b => 10 * a + b) 0
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end Index
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/-- The type of lists of indices. -/
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def IndexList : Type := List (Index X)
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namespace IndexList
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variable {X : Type} [IndexNotation X] [Fintype X] [DecidableEq X]
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variable (l : IndexList X)
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/-- The number of indices in an index list. -/
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def numIndices : Nat := l.length
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/-- The map of from `Fin s.numIndices` into colors associated to an index list. -/
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def colorMap : Fin l.numIndices → X :=
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fun i => (l.get i).toColor
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/-- The map of from `Fin s.numIndices` into the natural numbers associated to an index list. -/
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def idMap : Fin l.numIndices → Nat :=
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fun i => (l.get i).id
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/-- Given a list of indices a subset of `Fin l.numIndices × Index X`
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of pairs of positions in `l` and the corresponding item in `l`. -/
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def toPosSet (l : IndexList X) : Set (Fin l.numIndices × Index X) :=
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{(i, l.get i) | i : Fin l.numIndices}
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/-- Equivalence between `toPosSet` and `Fin l.numIndices`. -/
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def toPosSetEquiv (l : IndexList X) : l.toPosSet ≃ Fin l.numIndices where
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toFun := fun x => x.1.1
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invFun := fun x => ⟨(x, l.get x), by simp [toPosSet]⟩
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left_inv x := by
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have hx := x.prop
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simp [toPosSet] at hx
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simp only [List.get_eq_getElem]
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obtain ⟨i, hi⟩ := hx
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have hi2 : i = x.1.1 := by
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obtain ⟨val, property⟩ := x
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obtain ⟨fst, snd⟩ := val
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simp_all only [Prod.mk.injEq]
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subst hi2
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simp_all only [Subtype.coe_eta]
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right_inv := by
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intro x
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rfl
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lemma toPosSet_is_finite (l : IndexList X) : l.toPosSet.Finite :=
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Finite.intro l.toPosSetEquiv
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instance : Fintype l.toPosSet where
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elems := Finset.map l.toPosSetEquiv.symm.toEmbedding Finset.univ
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complete := by
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intro x
|
||||
simp_all only [Finset.mem_map_equiv, Equiv.symm_symm, Finset.mem_univ]
|
||||
|
||||
/-- Given a list of indices a finite set of `Fin l.numIndices × Index X`
|
||||
of pairs of positions in `l` and the corresponding item in `l`. -/
|
||||
def toPosFinset (l : IndexList X) : Finset (Fin l.numIndices × Index X) :=
|
||||
l.toPosSet.toFinset
|
||||
|
||||
instance : HAppend (IndexList X) (IndexList X) (IndexList X) :=
|
||||
@instHAppendOfAppend (List (Index X)) List.instAppend
|
||||
|
||||
def fromFinMap {n : ℕ} (f : Fin n → Index X) : IndexList X :=
|
||||
(Fin.list n).map f
|
||||
|
||||
@[simp]
|
||||
lemma fromFinMap_numIndices {n : ℕ} (f : Fin n → Index X) :
|
||||
(fromFinMap f).numIndices = n := by
|
||||
simp [fromFinMap, numIndices]
|
||||
|
||||
end IndexList
|
||||
|
||||
/-- A string of indices to be associated with a tensor.
|
||||
E.g. `ᵘ⁰ᵤ₂₆₀ᵘ³`. -/
|
||||
def IndexString : Type := {s : String // listCharIndexStringBool X s.toList = true}
|
||||
|
||||
namespace IndexString
|
||||
|
||||
variable {X : Type} [IndexNotation X] [Fintype X] [DecidableEq X]
|
||||
|
||||
/-- The character list associated with a index string. -/
|
||||
def toCharList (s : IndexString X) : List Char := s.val.toList
|
||||
|
||||
/-- The char list of an index string satisfies `listCharIndexString`. -/
|
||||
lemma listCharIndexString (s : IndexString X) : listCharIndexString X s.toCharList := by
|
||||
rw [listCharIndexString_iff_bool]
|
||||
exact s.prop
|
||||
|
||||
/-- The indices associated to an index string. -/
|
||||
def toIndexList (s : IndexString X) : IndexList X :=
|
||||
(listCharIndexStringTolistCharIndex X s.toCharList (listCharIndexString s)).map
|
||||
fun x => Index.ofCharList x.1 x.2
|
||||
|
||||
end IndexString
|
||||
|
||||
end IndexNotation
|
||||
|
||||
instance : IndexNotation realTensorColor.Color where
|
||||
charList := {'ᵘ', 'ᵤ'}
|
||||
notaEquiv :=
|
||||
{toFun := fun x =>
|
||||
match x with
|
||||
| .up => ⟨'ᵘ', by decide⟩
|
||||
| .down => ⟨'ᵤ', by decide⟩,
|
||||
invFun := fun x =>
|
||||
match x with
|
||||
| ⟨'ᵘ', _⟩ => .up
|
||||
| ⟨'ᵤ', _⟩ => .down
|
||||
| _ => .up,
|
||||
left_inv := by
|
||||
intro x
|
||||
fin_cases x <;> rfl,
|
||||
right_inv := by
|
||||
intro x
|
||||
fin_cases x <;> rfl}
|
||||
|
||||
namespace TensorColor
|
||||
|
||||
variable {n m : ℕ}
|
||||
|
||||
variable {R : Type} [CommSemiring R] (𝓣 : TensorStructure R)
|
||||
|
||||
variable {d : ℕ} {X Y Y' Z W : Type} [Fintype X] [DecidableEq X] [Fintype Y] [DecidableEq Y]
|
||||
[Fintype Y'] [DecidableEq Y'] [Fintype Z] [DecidableEq Z] [Fintype W] [DecidableEq W]
|
||||
{cX cX2 : X → 𝓣.Color} {cY : Y → 𝓣.Color} {cZ : Z → 𝓣.Color}
|
||||
{cW : W → 𝓣.Color} {cY' : Y' → 𝓣.Color} {μ ν: 𝓣.Color}
|
||||
{cn : Fin n → 𝓣.Color} {cm : Fin m → 𝓣.Color}
|
||||
|
||||
variable (𝓒 : TensorColor)
|
||||
variable [IndexNotation 𝓒.Color] [Fintype 𝓒.Color] [DecidableEq 𝓒.Color]
|
||||
|
||||
open IndexNotation
|
||||
|
||||
/-- The proposition on an `i : Fin s.length` such the corresponding element of
|
||||
`s` does not contract with any other element (i.e. share an index). -/
|
||||
def NoContr (s : IndexList 𝓒.Color) (i : Fin s.length) : Prop :=
|
||||
∀ j, i ≠ j → s.idMap i ≠ s.idMap j
|
||||
|
||||
instance (i : Fin s.length) : Decidable (NoContr 𝓒 s i) :=
|
||||
Fintype.decidableForallFintype
|
||||
|
||||
/-- The finset of indices of `s` corresponding to elements which do not contract. -/
|
||||
def noContrFinset (s : IndexList 𝓒.Color) : Finset (Fin s.length) :=
|
||||
Finset.univ.filter (𝓒.NoContr s)
|
||||
|
||||
/-- An eqiuvalence between the subtype of indices of `s` which do not contract and
|
||||
`Fin _`. -/
|
||||
def noContrSubtypeEquiv (s : IndexList 𝓒.Color) :
|
||||
{i : Fin s.length // NoContr 𝓒 s i} ≃ Fin (𝓒.noContrFinset s).card :=
|
||||
(Equiv.subtypeEquivRight (by
|
||||
intro x
|
||||
simp only [noContrFinset, Finset.mem_filter, Finset.mem_univ, true_and])).trans
|
||||
(Finset.orderIsoOfFin (𝓒.noContrFinset s) (by rfl)).toEquiv.symm
|
||||
|
||||
/-- The subtype of indices `s` which do contract. -/
|
||||
def contrSubtype (s : IndexList 𝓒.Color) : Type :=
|
||||
{i : Fin s.length // ¬ NoContr 𝓒 s i}
|
||||
|
||||
instance (s : IndexList 𝓒.Color) : Fintype (𝓒.contrSubtype s) :=
|
||||
Subtype.fintype fun x => ¬𝓒.NoContr s x
|
||||
|
||||
instance (s : IndexList 𝓒.Color) : DecidableEq (𝓒.contrSubtype s) :=
|
||||
Subtype.instDecidableEq
|
||||
|
||||
/-- Given a `i : 𝓒.contrSubtype s` the proposition on a `j` in `Fin s.length` for
|
||||
it to be an index of `s` contracting with `i`. -/
|
||||
def getDualProp {s : IndexList 𝓒.Color} (i : 𝓒.contrSubtype s) (j : Fin s.length) : Prop :=
|
||||
i.1 ≠ j ∧ s.idMap i.1 = s.idMap j
|
||||
|
||||
instance {s : IndexList 𝓒.Color} (i : 𝓒.contrSubtype s) (j : Fin s.length) :
|
||||
Decidable (𝓒.getDualProp i j) :=
|
||||
instDecidableAnd
|
||||
|
||||
/-- Given a `i : 𝓒.contrSubtype s` the index of `s` contracting with `i`. -/
|
||||
def getDualFin {s : IndexList 𝓒.Color} (i : 𝓒.contrSubtype s) : Fin s.length :=
|
||||
(Fin.find (𝓒.getDualProp i)).get (by simpa [NoContr, Fin.isSome_find_iff] using i.prop)
|
||||
|
||||
lemma some_getDualFin_eq_find {s : IndexList 𝓒.Color} (i : 𝓒.contrSubtype s) :
|
||||
Fin.find (𝓒.getDualProp i) = some (getDualFin 𝓒 i) := by
|
||||
simp [getDualFin]
|
||||
|
||||
lemma getDualFin_not_NoContr {s : IndexList 𝓒.Color} (i : 𝓒.contrSubtype s) :
|
||||
¬ NoContr 𝓒 s (getDualFin 𝓒 i) := by
|
||||
have h := 𝓒.some_getDualFin_eq_find i
|
||||
rw [Fin.find_eq_some_iff] at h
|
||||
simp [NoContr]
|
||||
exact ⟨i.1, And.intro (fun a => h.1.1 a.symm) h.1.2.symm⟩
|
||||
|
||||
/-- The dual index of an element of `𝓒.contrSubtype s`, that is the index
|
||||
contracting with it. -/
|
||||
def getDual {s : IndexList 𝓒.Color} (i : 𝓒.contrSubtype s) : 𝓒.contrSubtype s :=
|
||||
⟨getDualFin 𝓒 i, getDualFin_not_NoContr 𝓒 i⟩
|
||||
|
||||
lemma getDual_id {s : IndexList 𝓒.Color} (i : 𝓒.contrSubtype s) :
|
||||
s.idMap i.1 = s.idMap (getDual 𝓒 i).1 := by
|
||||
simp [getDual]
|
||||
have h1 := 𝓒.some_getDualFin_eq_find i
|
||||
rw [Fin.find_eq_some_iff] at h1
|
||||
simp only [getDualProp, ne_eq, and_imp] at h1
|
||||
exact h1.1.2
|
||||
|
||||
lemma getDual_neq_self {s : IndexList 𝓒.Color} (i : 𝓒.contrSubtype s) :
|
||||
i ≠ 𝓒.getDual i := by
|
||||
have h1 := 𝓒.some_getDualFin_eq_find i
|
||||
rw [Fin.find_eq_some_iff] at h1
|
||||
exact ne_of_apply_ne Subtype.val h1.1.1
|
||||
|
||||
/-- An index list is allowed if every contracting index has exactly one dual,
|
||||
and the color of the dual is dual to the color of the index. -/
|
||||
def IndexListColorProp (s : IndexList 𝓒.Color) : Prop :=
|
||||
(∀ (i j : 𝓒.contrSubtype s), 𝓒.getDualProp i j.1 → j = 𝓒.getDual i) ∧
|
||||
(∀ (i : 𝓒.contrSubtype s), s.colorMap i.1 = 𝓒.τ (s.colorMap (𝓒.getDual i).1))
|
||||
|
||||
/-- The type of index lists which satisfy `IndexListColorProp`. -/
|
||||
def IndexListColor : Type := {s : IndexList 𝓒.Color // 𝓒.IndexListColorProp s}
|
||||
|
||||
instance : Coe (IndexListColor 𝓒) (IndexList 𝓒.Color) := ⟨fun x => x.val⟩
|
||||
|
||||
@[simp]
|
||||
lemma getDual_getDual {s : IndexListColor 𝓒} (i : 𝓒.contrSubtype s) :
|
||||
getDual 𝓒 (getDual 𝓒 i) = i := by
|
||||
refine (s.prop.1 (getDual 𝓒 i) i ?_).symm
|
||||
simp [getDualProp]
|
||||
apply And.intro
|
||||
exact Subtype.coe_ne_coe.mpr (getDual_neq_self 𝓒 i).symm
|
||||
exact (getDual_id 𝓒 i).symm
|
||||
|
||||
/-- The set of contracting ordered pairs of indices. -/
|
||||
def contrPairSet (s : IndexList 𝓒.Color) : Set (𝓒.contrSubtype s × 𝓒.contrSubtype s) :=
|
||||
{p | p.1.1 < p.2.1 ∧ s.idMap p.1.1 = s.idMap p.2.1}
|
||||
|
||||
lemma getDual_lt_self_mem_contrPairSet {s : IndexList 𝓒.Color} {i : 𝓒.contrSubtype s}
|
||||
(h : (getDual 𝓒 i).1 < i.1) : (getDual 𝓒 i, i) ∈ 𝓒.contrPairSet s :=
|
||||
And.intro h (𝓒.getDual_id i).symm
|
||||
|
||||
lemma getDual_not_lt_self_mem_contrPairSet {s : IndexList 𝓒.Color} {i : 𝓒.contrSubtype s}
|
||||
(h : ¬ (getDual 𝓒 i).1 < i.1) : (i, getDual 𝓒 i) ∈ 𝓒.contrPairSet s := by
|
||||
apply And.intro
|
||||
have h1 := 𝓒.getDual_neq_self i
|
||||
simp only [Subtype.coe_lt_coe, gt_iff_lt]
|
||||
simp at h
|
||||
exact lt_of_le_of_ne h h1
|
||||
simp only
|
||||
exact getDual_id 𝓒 i
|
||||
|
||||
lemma contrPairSet_fst_eq_dual_snd (s : IndexListColor 𝓒)
|
||||
(x : 𝓒.contrPairSet s) : x.1.1 = getDual 𝓒 x.1.2 :=
|
||||
(s.prop.1 (x.1.2) x.1.1 (And.intro (Fin.ne_of_gt x.2.1) x.2.2.symm))
|
||||
|
||||
lemma contrPairSet_snd_eq_dual_fst (s : IndexListColor 𝓒)
|
||||
(x : 𝓒.contrPairSet s) : x.1.2 = getDual 𝓒 x.1.1 := by
|
||||
rw [contrPairSet_fst_eq_dual_snd, getDual_getDual]
|
||||
|
||||
lemma contrPairSet_dual_snd_lt_self (s : IndexListColor 𝓒)
|
||||
(x : 𝓒.contrPairSet s) : (getDual 𝓒 x.1.2).1 < x.1.2.1 := by
|
||||
rw [← 𝓒.contrPairSet_fst_eq_dual_snd]
|
||||
exact x.2.1
|
||||
|
||||
/-- An equivalence between two coppies of `𝓒.contrPairSet s` and `𝓒.contrSubtype s`.
|
||||
This equivalence exists due to the ordering on pairs in `𝓒.contrPairSet s`. -/
|
||||
def contrPairEquiv (s : IndexListColor 𝓒) :
|
||||
𝓒.contrPairSet s ⊕ 𝓒.contrPairSet s ≃ 𝓒.contrSubtype s where
|
||||
toFun x :=
|
||||
match x with
|
||||
| Sum.inl p => p.1.2
|
||||
| Sum.inr p => p.1.1
|
||||
invFun x :=
|
||||
if h : (𝓒.getDual x).1 < x.1 then
|
||||
Sum.inl ⟨(𝓒.getDual x, x), 𝓒.getDual_lt_self_mem_contrPairSet h⟩
|
||||
else
|
||||
Sum.inr ⟨(x, 𝓒.getDual x), 𝓒.getDual_not_lt_self_mem_contrPairSet h⟩
|
||||
left_inv x := by
|
||||
match x with
|
||||
| Sum.inl x =>
|
||||
simp only [Subtype.coe_lt_coe]
|
||||
rw [dif_pos]
|
||||
simp [← 𝓒.contrPairSet_fst_eq_dual_snd]
|
||||
exact 𝓒.contrPairSet_dual_snd_lt_self s _
|
||||
| Sum.inr x =>
|
||||
simp only [Subtype.coe_lt_coe]
|
||||
rw [dif_neg]
|
||||
simp only [← 𝓒.contrPairSet_snd_eq_dual_fst, Prod.mk.eta, Subtype.coe_eta]
|
||||
rw [← 𝓒.contrPairSet_snd_eq_dual_fst]
|
||||
have h1 := x.2.1
|
||||
simp only [not_lt, ge_iff_le]
|
||||
exact le_of_lt h1
|
||||
right_inv x := by
|
||||
by_cases h1 : (getDual 𝓒 x).1 < x.1
|
||||
simp only [h1, ↓reduceDIte]
|
||||
simp only [h1, ↓reduceDIte]
|
||||
|
||||
@[simp]
|
||||
lemma contrPairEquiv_apply_inr (s : IndexListColor 𝓒)
|
||||
(x : 𝓒.contrPairSet s) : 𝓒.contrPairEquiv s (Sum.inr x) = x.1.1 := by
|
||||
simp [contrPairEquiv]
|
||||
|
||||
@[simp]
|
||||
lemma contrPairEquiv_apply_inl (s : IndexListColor 𝓒)
|
||||
(x : 𝓒.contrPairSet s) : 𝓒.contrPairEquiv s (Sum.inl x) = x.1.2 := by
|
||||
simp [contrPairEquiv]
|
||||
|
||||
/-- An equivalence between `Fin s.length` and
|
||||
`(𝓒.contrPairSet s ⊕ 𝓒.contrPairSet s) ⊕ Fin (𝓒.noContrFinset s).card`, which
|
||||
can be used for contractions. -/
|
||||
def splitContr (s : IndexListColor 𝓒) :
|
||||
Fin s.1.length ≃ (𝓒.contrPairSet s ⊕ 𝓒.contrPairSet s) ⊕ Fin (𝓒.noContrFinset s).card :=
|
||||
(Equiv.sumCompl (𝓒.NoContr s)).symm.trans <|
|
||||
(Equiv.sumComm { i // 𝓒.NoContr s i} { i // ¬ 𝓒.NoContr s i}).trans <|
|
||||
Equiv.sumCongr (𝓒.contrPairEquiv s).symm (𝓒.noContrSubtypeEquiv s)
|
||||
|
||||
lemma splitContr_map (s : IndexListColor 𝓒) :
|
||||
s.1.colorMap ∘ (𝓒.splitContr s).symm ∘ Sum.inl ∘ Sum.inl =
|
||||
𝓒.τ ∘ s.1.colorMap ∘ (𝓒.splitContr s).symm ∘ Sum.inl ∘ Sum.inr := by
|
||||
funext x
|
||||
simp [splitContr, contrPairEquiv_apply_inr]
|
||||
erw [contrPairEquiv_apply_inr, contrPairEquiv_apply_inl]
|
||||
rw [contrPairSet_fst_eq_dual_snd _ _]
|
||||
exact s.prop.2 _
|
||||
|
||||
/-!
|
||||
|
||||
## Contraction of an IndexListColor
|
||||
|
||||
-/
|
||||
|
||||
/-- The proposition on a `IndexList` for it to have no contracting
|
||||
indices. -/
|
||||
def HasNoContr (s : IndexList 𝓒.Color) : Prop :=
|
||||
∀ i, 𝓒.NoContr s i
|
||||
|
||||
instance (s : IndexList 𝓒.Color) (h : 𝓒.HasNoContr s) : IsEmpty (𝓒.contrSubtype s) := by
|
||||
rw [isEmpty_iff]
|
||||
intro a
|
||||
exact h a.1 a.1 (fun _ => a.2 (h a.1)) rfl
|
||||
|
||||
lemma indexListColorProp_of_hasNoContr {s : IndexList 𝓒.Color} (h : 𝓒.HasNoContr s) :
|
||||
𝓒.IndexListColorProp s := by
|
||||
simp [IndexListColorProp]
|
||||
haveI : IsEmpty (𝓒.contrSubtype s) := 𝓒.instIsEmptyContrSubtypeOfHasNoContr s h
|
||||
simp
|
||||
|
||||
def contrIndexList (s : IndexListColor 𝓒) : IndexList 𝓒.Color :=
|
||||
IndexList.fromFinMap (fun i => s.1.get ((𝓒.noContrSubtypeEquiv s).symm i))
|
||||
|
||||
@[simp]
|
||||
lemma contrIndexList_numIndices (s : IndexListColor 𝓒) :
|
||||
(𝓒.contrIndexList s).numIndices = (𝓒.noContrFinset s).card := by
|
||||
simp [contrIndexList]
|
||||
|
||||
@[simp]
|
||||
lemma contrIndexList_idMap_apply (s : IndexListColor 𝓒) (i : Fin (𝓒.contrIndexList s).numIndices) :
|
||||
(𝓒.contrIndexList s).idMap i =
|
||||
s.1.idMap ((𝓒.noContrSubtypeEquiv s).symm (Fin.cast (by simp) i)).1 := by
|
||||
simp [contrIndexList, IndexList.fromFinMap, IndexList.idMap]
|
||||
rfl
|
||||
|
||||
@[simp]
|
||||
lemma idMap_noContrSubtypeEquiv_neq (s : IndexListColor 𝓒) (i j : Fin (𝓒.noContrFinset ↑s).card)
|
||||
(h : i ≠ j) :
|
||||
s.1.idMap ((𝓒.noContrSubtypeEquiv s).symm i).1 ≠ s.1.idMap ((𝓒.noContrSubtypeEquiv s).symm j).1 := by
|
||||
have hi := ((𝓒.noContrSubtypeEquiv s).symm i).2
|
||||
simp [NoContr] at hi
|
||||
have hj := hi ((𝓒.noContrSubtypeEquiv s).symm j)
|
||||
apply hj
|
||||
rw [@SetCoe.ext_iff]
|
||||
erw [Equiv.apply_eq_iff_eq]
|
||||
exact h
|
||||
|
||||
lemma contrIndexList_hasNoContr (s : IndexListColor 𝓒) : 𝓒.HasNoContr (𝓒.contrIndexList s) := by
|
||||
intro i
|
||||
simp [NoContr]
|
||||
intro j h
|
||||
refine 𝓒.idMap_noContrSubtypeEquiv_neq s _ _ ?_
|
||||
rw [@Fin.ne_iff_vne]
|
||||
simp only [Fin.coe_cast, ne_eq]
|
||||
exact Fin.val_ne_of_ne h
|
||||
|
||||
def contrIndexListColor (s : IndexListColor 𝓒) : IndexListColor 𝓒 :=
|
||||
⟨𝓒.contrIndexList s, 𝓒.indexListColorProp_of_hasNoContr (𝓒.contrIndexList_hasNoContr s)⟩
|
||||
|
||||
/-!
|
||||
|
||||
## Equivalence relation on IndexListColor
|
||||
|
||||
-/
|
||||
|
||||
/-- Two index lists are related if there contracted lists have the same id's for indices,
|
||||
and the color of indices with the same id sit are the same.
|
||||
This will allow us to add and compare tensors. -/
|
||||
def indexColorRel (s1 s2 : IndexListColor 𝓒) : Prop :=
|
||||
List.Perm ((𝓒.contrIndexListColor s1).1.map Index.id) ((𝓒.contrIndexListColor s2).1.map Index.id)
|
||||
∧ ∀ (l1 : (𝓒.contrIndexListColor s1).1.toPosFinset)
|
||||
(l2 : (𝓒.contrIndexListColor s2).1.toPosFinset),
|
||||
l1.1.2.id = l2.1.2.id → l1.1.2.toColor = l2.1.2.toColor
|
||||
|
||||
/-! TODO: Show that `indexColorRel` is indeed an equivalence relation. -/
|
||||
|
||||
/-!
|
||||
|
||||
## Joining two IndexListColor
|
||||
|
||||
-/
|
||||
def joinIndexListColor (s1 s2 : IndexListColor 𝓒) (h : 𝓒.IndexListColorProp (s1.1 ++ s2.1)) :
|
||||
IndexListColor 𝓒 := ⟨s1.1 ++ s2.1, h⟩
|
||||
|
||||
@[simp]
|
||||
lemma joinIndexListColor_len {s1 s2 : IndexListColor 𝓒} (h : 𝓒.IndexListColorProp (s1.1 ++ s2.1))
|
||||
(h1 : n = s1.1.length) (h2 : m = s2.1.length) :
|
||||
n + m = (𝓒.joinIndexListColor s1 s2 h).1.length := by
|
||||
erw [List.length_append]
|
||||
simp only [h1, h2]
|
||||
|
||||
/-!
|
||||
|
||||
## Permutation between two IndexListColor
|
||||
|
||||
-/
|
||||
|
||||
|
||||
|
||||
end TensorColor
|
||||
|
||||
/-!
|
||||
|
||||
## Index notation with respect to tensor structure
|
||||
|
||||
-/
|
||||
namespace TensorStructure
|
||||
open TensorColor
|
||||
open IndexNotation
|
||||
variable (𝓣 : TensorStructure R)
|
||||
|
||||
variable {d : ℕ} {X Y Y' Z W : Type} [Fintype X] [DecidableEq X] [Fintype Y] [DecidableEq Y]
|
||||
[Fintype Y'] [DecidableEq Y'] [Fintype Z] [DecidableEq Z] [Fintype W] [DecidableEq W]
|
||||
{cX cX2 : X → 𝓣.Color} {cY : Y → 𝓣.Color} {cZ : Z → 𝓣.Color}
|
||||
{cW : W → 𝓣.Color} {cY' : Y' → 𝓣.Color} {μ ν η : 𝓣.Color}
|
||||
|
||||
variable [IndexNotation 𝓣.Color] [Fintype 𝓣.Color] [DecidableEq 𝓣.Color]
|
||||
|
||||
structure TensorIndex (cn : Fin n → 𝓣.Color) where
|
||||
tensor : 𝓣.Tensor cn
|
||||
index : IndexListColor 𝓣.toTensorColor
|
||||
nat_eq : n = index.1.length
|
||||
quot_eq : 𝓣.colorQuot ∘ index.1.colorMap ∘ Fin.cast nat_eq = 𝓣.colorQuot ∘ cn
|
||||
|
||||
namespace TensorIndex
|
||||
|
||||
variable {𝓣 : TensorStructure R} [IndexNotation 𝓣.Color] [Fintype 𝓣.Color] [DecidableEq 𝓣.Color]
|
||||
variable {n m : ℕ} {cn : Fin n → 𝓣.Color} {cm : Fin m → 𝓣.Color} (T : TensorIndex 𝓣 cn)
|
||||
section noncomputable
|
||||
|
||||
def smul (r : R) : TensorIndex 𝓣 cn := ⟨r • T.tensor, T.index, T.nat_eq, T.quot_eq⟩
|
||||
|
||||
end
|
||||
|
||||
end TensorIndex
|
||||
|
||||
end TensorStructure
|
||||
406
HepLean/SpaceTime/LorentzTensor/IndexNotation/Basic.lean
Normal file
406
HepLean/SpaceTime/LorentzTensor/IndexNotation/Basic.lean
Normal file
|
|
@ -0,0 +1,406 @@
|
|||
/-
|
||||
Copyright (c) 2024 Joseph Tooby-Smith. All rights reserved.
|
||||
Released under Apache 2.0 license as described in the file LICENSE.
|
||||
Authors: Joseph Tooby-Smith
|
||||
-/
|
||||
import HepLean.SpaceTime.LorentzTensor.Real.Basic
|
||||
/-!
|
||||
|
||||
# Index notation for a type
|
||||
|
||||
In this file we will define an index of a Lorentz tensor as a
|
||||
string satisfying certain properties.
|
||||
|
||||
For example, the string `ᵘ¹²` is an index of a real Lorentz tensors.
|
||||
The first character `ᵘ` specifies the color of the index, and the subsequent characters
|
||||
`¹²` specify the id of the index.
|
||||
|
||||
Strings of indices e.g. `ᵘ¹²ᵤ₄₃`` are defined elsewhere.
|
||||
|
||||
-/
|
||||
|
||||
open Lean
|
||||
open String
|
||||
|
||||
/-- The class defining index notation on a type `X`.
|
||||
Normally `X` will be taken as the type of colors of a `TensorStructure`. -/
|
||||
class IndexNotation (X : Type) where
|
||||
/-- The list of characters describing the index notation e.g.
|
||||
`{'ᵘ', 'ᵤ'}` for real tensors. -/
|
||||
charList : Finset Char
|
||||
/-- An equivalence between `X` (colors of indices) and `charList`.
|
||||
This takes every color of index to its notation character. -/
|
||||
notaEquiv : X ≃ charList
|
||||
|
||||
namespace IndexNotation
|
||||
|
||||
variable (X : Type) [IndexNotation X]
|
||||
variable [Fintype X] [DecidableEq X]
|
||||
|
||||
/-!
|
||||
|
||||
## Lists of characters forming an index
|
||||
|
||||
Here we define `listCharIndex` and properties thereof.
|
||||
|
||||
-/
|
||||
|
||||
/-- The map taking a color to its notation character. -/
|
||||
def nota {X : Type} [IndexNotation X] (x : X) : Char :=
|
||||
(IndexNotation.notaEquiv).toFun x
|
||||
|
||||
/-- A character is a `notation character` if it is in `charList`. -/
|
||||
def isNotationChar (c : Char) : Bool :=
|
||||
if c ∈ charList X then true else false
|
||||
|
||||
/-- A character is a numeric superscript if it is e.g. `⁰`, `¹`, etc. -/
|
||||
def isNumericSupscript (c : Char) : Bool :=
|
||||
c = '¹' ∨ c = '²' ∨ c = '³' ∨ c = '⁴' ∨ c = '⁵' ∨ c = '⁶' ∨ c = '⁷' ∨ c = '⁸' ∨ c = '⁹' ∨ c = '⁰'
|
||||
|
||||
/-- Given a character `f` which is a notation character, this is true if `c`
|
||||
is a subscript when `f` is a subscript or `c` is a superscript when `f` is a
|
||||
superscript. -/
|
||||
def IsIndexId (f : Char) (c : Char) : Bool :=
|
||||
(isSubScriptAlnum f ∧ isNumericSubscript c) ∨
|
||||
(¬ isSubScriptAlnum f ∧ isNumericSupscript c)
|
||||
|
||||
/-- The proposition for a list of characters to be the tail of an index
|
||||
e.g. `['¹', '⁷', ...]` -/
|
||||
def listCharIndexTail (f : Char) (l : List Char) : Prop :=
|
||||
l ≠ [] ∧ List.all l (fun c => IsIndexId f c)
|
||||
|
||||
instance : Decidable (listCharIndexTail f l) := instDecidableAnd
|
||||
|
||||
/-- The proposition for a list of characters to be the characters of an index
|
||||
e.g. `['ᵘ', '¹', '⁷', ...]` -/
|
||||
def listCharIndex (l : List Char) : Prop :=
|
||||
if h : l = [] then True
|
||||
else
|
||||
let sfst := l.head h
|
||||
if ¬ isNotationChar X sfst then False
|
||||
else
|
||||
listCharIndexTail sfst l.tail
|
||||
|
||||
/-- An auxillary rewrite lemma to prove that `listCharIndex` is decidable. -/
|
||||
lemma listCharIndex_iff (l : List Char) : listCharIndex X l
|
||||
↔ (if h : l = [] then True else
|
||||
let sfst := l.head h
|
||||
if ¬ isNotationChar X sfst then False
|
||||
else listCharIndexTail sfst l.tail) := by
|
||||
rw [listCharIndex]
|
||||
|
||||
instance : Decidable (listCharIndex X l) :=
|
||||
@decidable_of_decidable_of_iff _ _
|
||||
(@instDecidableDite _ _ _ _ _ <|
|
||||
fun _ => @instDecidableDite _ _ _ _ _ <|
|
||||
fun _ => instDecidableListCharIndexTail)
|
||||
(listCharIndex_iff X l).symm
|
||||
|
||||
/-!
|
||||
|
||||
## The definition of an index and its properties
|
||||
|
||||
-/
|
||||
|
||||
/-- An index is a non-empty string satisfying the condtion `listCharIndex`,
|
||||
e.g. `ᵘ¹²` or `ᵤ₄₃` etc. -/
|
||||
def Index : Type := {s : String // listCharIndex X s.toList ∧ s.toList ≠ []}
|
||||
|
||||
namespace Index
|
||||
|
||||
variable {X : Type} [IndexNotation X] [Fintype X] [DecidableEq X]
|
||||
|
||||
/-- Creats an index from a non-empty list of characters satisfying `listCharIndex`. -/
|
||||
def ofCharList (l : List Char) (h : listCharIndex X l ∧ l ≠ []) : Index X := ⟨l.asString, h⟩
|
||||
|
||||
instance : ToString (Index X) := ⟨fun i => i.val⟩
|
||||
|
||||
/-- Gets the first character in an index e.g. `ᵘ` as an element of `charList X`. -/
|
||||
def head (s : Index X) : charList X :=
|
||||
⟨s.val.toList.head (s.prop.2), by
|
||||
have h := s.prop.1
|
||||
have h2 := s.prop.2
|
||||
simp [listCharIndex] at h
|
||||
simp_all only [toList, ne_eq, Bool.not_eq_true, ↓reduceDIte]
|
||||
simpa [isNotationChar] using h.1⟩
|
||||
|
||||
/-- The color associated to an index. -/
|
||||
def toColor (s : Index X) : X := (IndexNotation.notaEquiv).invFun s.head
|
||||
|
||||
/-- A map from super and subscript numerical characters to the natural numbers,
|
||||
returning `0` on all other characters. -/
|
||||
def charToNat (c : Char) : Nat :=
|
||||
match c with
|
||||
| '₀' => 0
|
||||
| '₁' => 1
|
||||
| '₂' => 2
|
||||
| '₃' => 3
|
||||
| '₄' => 4
|
||||
| '₅' => 5
|
||||
| '₆' => 6
|
||||
| '₇' => 7
|
||||
| '₈' => 8
|
||||
| '₉' => 9
|
||||
| '⁰' => 0
|
||||
| '¹' => 1
|
||||
| '²' => 2
|
||||
| '³' => 3
|
||||
| '⁴' => 4
|
||||
| '⁵' => 5
|
||||
| '⁶' => 6
|
||||
| '⁷' => 7
|
||||
| '⁸' => 8
|
||||
| '⁹' => 9
|
||||
| _ => 0
|
||||
|
||||
/-- The numerical characters associated with an index. -/
|
||||
def tail (s : Index X) : List Char := s.val.toList.tail
|
||||
|
||||
/-- The natural numbers assocaited with an index. -/
|
||||
def tailNat (s : Index X) : List Nat := s.tail.map charToNat
|
||||
|
||||
/-- The id of an index, as a natural number. -/
|
||||
def id (s : Index X) : Nat := s.tailNat.foldl (fun a b => 10 * a + b) 0
|
||||
|
||||
end Index
|
||||
|
||||
/-!
|
||||
|
||||
## List of indices
|
||||
|
||||
-/
|
||||
|
||||
/-- The type of lists of indices. -/
|
||||
def IndexList : Type := List (Index X)
|
||||
|
||||
namespace IndexList
|
||||
|
||||
variable {X : Type} [IndexNotation X] [Fintype X] [DecidableEq X]
|
||||
|
||||
variable (l : IndexList X)
|
||||
|
||||
/-- The number of indices in an index list. -/
|
||||
def numIndices : Nat := l.length
|
||||
|
||||
/-- The map of from `Fin s.numIndices` into colors associated to an index list. -/
|
||||
def colorMap : Fin l.numIndices → X :=
|
||||
fun i => (l.get i).toColor
|
||||
|
||||
/-- The map of from `Fin s.numIndices` into the natural numbers associated to an index list. -/
|
||||
def idMap : Fin l.numIndices → Nat :=
|
||||
fun i => (l.get i).id
|
||||
|
||||
/-- Given a list of indices a subset of `Fin l.numIndices × Index X`
|
||||
of pairs of positions in `l` and the corresponding item in `l`. -/
|
||||
def toPosSet (l : IndexList X) : Set (Fin l.numIndices × Index X) :=
|
||||
{(i, l.get i) | i : Fin l.numIndices}
|
||||
|
||||
/-- Equivalence between `toPosSet` and `Fin l.numIndices`. -/
|
||||
def toPosSetEquiv (l : IndexList X) : l.toPosSet ≃ Fin l.numIndices where
|
||||
toFun := fun x => x.1.1
|
||||
invFun := fun x => ⟨(x, l.get x), by simp [toPosSet]⟩
|
||||
left_inv x := by
|
||||
have hx := x.prop
|
||||
simp [toPosSet] at hx
|
||||
simp only [List.get_eq_getElem]
|
||||
obtain ⟨i, hi⟩ := hx
|
||||
have hi2 : i = x.1.1 := by
|
||||
obtain ⟨val, property⟩ := x
|
||||
obtain ⟨fst, snd⟩ := val
|
||||
simp_all only [Prod.mk.injEq]
|
||||
subst hi2
|
||||
simp_all only [Subtype.coe_eta]
|
||||
right_inv := by
|
||||
intro x
|
||||
rfl
|
||||
|
||||
lemma toPosSet_is_finite (l : IndexList X) : l.toPosSet.Finite :=
|
||||
Finite.intro l.toPosSetEquiv
|
||||
|
||||
instance : Fintype l.toPosSet where
|
||||
elems := Finset.map l.toPosSetEquiv.symm.toEmbedding Finset.univ
|
||||
complete := by
|
||||
intro x
|
||||
simp_all only [Finset.mem_map_equiv, Equiv.symm_symm, Finset.mem_univ]
|
||||
|
||||
/-- Given a list of indices a finite set of `Fin l.numIndices × Index X`
|
||||
of pairs of positions in `l` and the corresponding item in `l`. -/
|
||||
def toPosFinset (l : IndexList X) : Finset (Fin l.numIndices × Index X) :=
|
||||
l.toPosSet.toFinset
|
||||
|
||||
instance : HAppend (IndexList X) (IndexList X) (IndexList X) :=
|
||||
@instHAppendOfAppend (List (Index X)) List.instAppend
|
||||
|
||||
/-- The construction of a list of indices from a map
|
||||
from `Fin n` to `Index X`. -/
|
||||
def fromFinMap {n : ℕ} (f : Fin n → Index X) : IndexList X :=
|
||||
(Fin.list n).map f
|
||||
|
||||
@[simp]
|
||||
lemma fromFinMap_numIndices {n : ℕ} (f : Fin n → Index X) :
|
||||
(fromFinMap f).numIndices = n := by
|
||||
simp [fromFinMap, numIndices]
|
||||
|
||||
/-!
|
||||
|
||||
## Contracted and non-contracting indices
|
||||
|
||||
-/
|
||||
|
||||
/-- The proposition on a element (or really index of element) of a index list
|
||||
`s` which is ture iff does not share an id with any other element.
|
||||
This tells us that it should not be contracted with any other element. -/
|
||||
def NoContr (i : Fin l.length) : Prop :=
|
||||
∀ j, i ≠ j → l.idMap i ≠ l.idMap j
|
||||
|
||||
instance (i : Fin l.length) : Decidable (l.NoContr i) :=
|
||||
Fintype.decidableForallFintype
|
||||
|
||||
/-- The finset of indices of an index list corresponding to elements which do not contract. -/
|
||||
def noContrFinset : Finset (Fin l.length) :=
|
||||
Finset.univ.filter l.NoContr
|
||||
|
||||
/-- An eqiuvalence between the subtype of indices of a index list `l` which do not contract and
|
||||
`Fin l.noContrFinset.card`. -/
|
||||
def noContrSubtypeEquiv : {i : Fin l.length // l.NoContr i} ≃ Fin l.noContrFinset.card :=
|
||||
(Equiv.subtypeEquivRight (fun x => by simp [noContrFinset])).trans
|
||||
(Finset.orderIsoOfFin l.noContrFinset rfl).toEquiv.symm
|
||||
|
||||
@[simp]
|
||||
lemma idMap_noContrSubtypeEquiv_neq (i j : Fin l.noContrFinset.card) (h : i ≠ j) :
|
||||
l.idMap (l.noContrSubtypeEquiv.symm i).1 ≠ l.idMap (l.noContrSubtypeEquiv.symm j).1 := by
|
||||
have hi := ((l.noContrSubtypeEquiv).symm i).2
|
||||
simp [NoContr] at hi
|
||||
have hj := hi ((l.noContrSubtypeEquiv).symm j)
|
||||
apply hj
|
||||
rw [@SetCoe.ext_iff]
|
||||
erw [Equiv.apply_eq_iff_eq]
|
||||
exact h
|
||||
|
||||
/-- The subtype of indices `l` which do contract. -/
|
||||
def contrSubtype : Type := {i : Fin l.length // ¬ l.NoContr i}
|
||||
|
||||
instance : Fintype l.contrSubtype :=
|
||||
Subtype.fintype fun x => ¬ l.NoContr x
|
||||
|
||||
instance : DecidableEq l.contrSubtype :=
|
||||
Subtype.instDecidableEq
|
||||
|
||||
/-!
|
||||
|
||||
## Getting the index which contracts with a given index
|
||||
|
||||
-/
|
||||
|
||||
/-- Given a `i : l.contrSubtype` the proposition on a `j` in `Fin s.length` for
|
||||
it to be an index of `s` contracting with `i`. -/
|
||||
def getDualProp (i : l.contrSubtype) (j : Fin l.length) : Prop :=
|
||||
i.1 ≠ j ∧ l.idMap i.1 = l.idMap j
|
||||
|
||||
instance (i : l.contrSubtype) (j : Fin l.length) :
|
||||
Decidable (l.getDualProp i j) :=
|
||||
instDecidableAnd
|
||||
|
||||
/-- Given a `i : l.contrSubtype` the index of `s` contracting with `i`. -/
|
||||
def getDualFin (i : l.contrSubtype) : Fin l.length :=
|
||||
(Fin.find (l.getDualProp i)).get (by simpa [NoContr, Fin.isSome_find_iff] using i.prop)
|
||||
|
||||
lemma some_getDualFin_eq_find (i : l.contrSubtype) :
|
||||
Fin.find (l.getDualProp i) = some (l.getDualFin i) := by
|
||||
simp [getDualFin]
|
||||
|
||||
lemma getDualFin_not_NoContr (i : l.contrSubtype) : ¬ l.NoContr (l.getDualFin i) := by
|
||||
have h := l.some_getDualFin_eq_find i
|
||||
rw [Fin.find_eq_some_iff] at h
|
||||
simp [NoContr]
|
||||
exact ⟨i.1, And.intro (fun a => h.1.1 a.symm) h.1.2.symm⟩
|
||||
|
||||
/-- The dual index of an element of `𝓒.contrSubtype s`, that is the index
|
||||
contracting with it. -/
|
||||
def getDual (i : l.contrSubtype) : l.contrSubtype :=
|
||||
⟨l.getDualFin i, l.getDualFin_not_NoContr i⟩
|
||||
|
||||
lemma getDual_id (i : l.contrSubtype) : l.idMap i.1 = l.idMap (l.getDual i).1 := by
|
||||
simp [getDual]
|
||||
have h1 := l.some_getDualFin_eq_find i
|
||||
rw [Fin.find_eq_some_iff] at h1
|
||||
simp only [getDualProp, ne_eq, and_imp] at h1
|
||||
exact h1.1.2
|
||||
|
||||
lemma getDual_neq_self (i : l.contrSubtype) : i ≠ l.getDual i := by
|
||||
have h1 := l.some_getDualFin_eq_find i
|
||||
rw [Fin.find_eq_some_iff] at h1
|
||||
exact ne_of_apply_ne Subtype.val h1.1.1
|
||||
|
||||
/-!
|
||||
|
||||
## Index lists with no contracting indices
|
||||
|
||||
-/
|
||||
|
||||
/-- The proposition on a `IndexList` for it to have no contracting
|
||||
indices. -/
|
||||
def HasNoContr : Prop := ∀ i, l.NoContr i
|
||||
|
||||
instance (h : l.HasNoContr) : IsEmpty l.contrSubtype := by
|
||||
rw [_root_.isEmpty_iff]
|
||||
intro a
|
||||
exact h a.1 a.1 (fun _ => a.2 (h a.1)) rfl
|
||||
|
||||
/-!
|
||||
|
||||
## The contracted index list
|
||||
|
||||
-/
|
||||
|
||||
/-- The index list of those indices of `l` which do not contract. -/
|
||||
def contrIndexList : IndexList X :=
|
||||
IndexList.fromFinMap (fun i => l.get (l.noContrSubtypeEquiv.symm i))
|
||||
|
||||
@[simp]
|
||||
lemma contrIndexList_numIndices : l.contrIndexList.numIndices = l.noContrFinset.card := by
|
||||
simp [contrIndexList]
|
||||
|
||||
@[simp]
|
||||
lemma contrIndexList_idMap_apply (i : Fin l.contrIndexList.numIndices) :
|
||||
l.contrIndexList.idMap i =
|
||||
l.idMap (l.noContrSubtypeEquiv.symm (Fin.cast (by simp) i)).1 := by
|
||||
simp [contrIndexList, IndexList.fromFinMap, IndexList.idMap]
|
||||
rfl
|
||||
|
||||
lemma contrIndexList_hasNoContr : HasNoContr l.contrIndexList := by
|
||||
intro i
|
||||
simp [NoContr]
|
||||
intro j h
|
||||
refine l.idMap_noContrSubtypeEquiv_neq _ _ ?_
|
||||
rw [@Fin.ne_iff_vne]
|
||||
simp only [Fin.coe_cast, ne_eq]
|
||||
exact Fin.val_ne_of_ne h
|
||||
|
||||
/-!
|
||||
|
||||
## Pairs of contracting indices
|
||||
|
||||
-/
|
||||
|
||||
/-- The set of contracting ordered pairs of indices. -/
|
||||
def contrPairSet : Set (l.contrSubtype × l.contrSubtype) :=
|
||||
{p | p.1.1 < p.2.1 ∧ l.idMap p.1.1 = l.idMap p.2.1}
|
||||
|
||||
lemma getDual_lt_self_mem_contrPairSet {i : l.contrSubtype}
|
||||
(h : (l.getDual i).1 < i.1) : (l.getDual i, i) ∈ l.contrPairSet :=
|
||||
And.intro h (l.getDual_id i).symm
|
||||
|
||||
lemma getDual_not_lt_self_mem_contrPairSet {i : l.contrSubtype}
|
||||
(h : ¬ (l.getDual i).1 < i.1) : (i, l.getDual i) ∈ l.contrPairSet := by
|
||||
apply And.intro
|
||||
have h1 := l.getDual_neq_self i
|
||||
simp only [Subtype.coe_lt_coe, gt_iff_lt]
|
||||
simp at h
|
||||
exact lt_of_le_of_ne h h1
|
||||
simp only
|
||||
exact l.getDual_id i
|
||||
|
||||
end IndexList
|
||||
|
||||
end IndexNotation
|
||||
|
|
@ -0,0 +1,178 @@
|
|||
/-
|
||||
Copyright (c) 2024 Joseph Tooby-Smith. All rights reserved.
|
||||
Released under Apache 2.0 license as described in the file LICENSE.
|
||||
Authors: Joseph Tooby-Smith
|
||||
-/
|
||||
import HepLean.SpaceTime.LorentzTensor.IndexNotation.Basic
|
||||
/-!
|
||||
|
||||
# Index lists with color conditions
|
||||
|
||||
Here we consider `IndexListColor` which is a subtype of all lists of indices
|
||||
on those where the elements to be contracted have consistent colors with respect to
|
||||
a Tensor Color structure.
|
||||
|
||||
-/
|
||||
|
||||
namespace IndexNotation
|
||||
|
||||
open IndexNotation
|
||||
|
||||
variable (𝓒 : TensorColor)
|
||||
variable [IndexNotation 𝓒.Color] [Fintype 𝓒.Color] [DecidableEq 𝓒.Color]
|
||||
|
||||
/-- An index list is allowed if every contracting index has exactly one dual,
|
||||
and the color of the dual is dual to the color of the index. -/
|
||||
def IndexListColorProp (l : IndexList 𝓒.Color) : Prop :=
|
||||
(∀ (i j : l.contrSubtype), l.getDualProp i j.1 → j = l.getDual i) ∧
|
||||
(∀ (i : l.contrSubtype), l.colorMap i.1 = 𝓒.τ (l.colorMap (l.getDual i).1))
|
||||
|
||||
/-- The type of index lists which satisfy `IndexListColorProp`. -/
|
||||
def IndexListColor : Type := {s : IndexList 𝓒.Color // IndexListColorProp 𝓒 s}
|
||||
|
||||
namespace IndexListColor
|
||||
|
||||
open IndexList
|
||||
|
||||
variable {𝓒 : TensorColor}
|
||||
variable [IndexNotation 𝓒.Color] [Fintype 𝓒.Color] [DecidableEq 𝓒.Color]
|
||||
variable (l : IndexListColor 𝓒)
|
||||
instance : Coe (IndexListColor 𝓒) (IndexList 𝓒.Color) := ⟨fun x => x.val⟩
|
||||
|
||||
lemma indexListColorProp_of_hasNoContr {s : IndexList 𝓒.Color} (h : s.HasNoContr) :
|
||||
IndexListColorProp 𝓒 s := by
|
||||
simp [IndexListColorProp]
|
||||
haveI : IsEmpty (s.contrSubtype) := s.instIsEmptyContrSubtypeOfHasNoContr h
|
||||
simp
|
||||
|
||||
/-!
|
||||
|
||||
## Contraction pairs for IndexListColor
|
||||
|
||||
-/
|
||||
|
||||
/-! TODO: Would be nice to get rid of all of the `.1` which appear here. -/
|
||||
@[simp]
|
||||
lemma getDual_getDual (i : l.1.contrSubtype) :
|
||||
l.1.getDual (l.1.getDual i) = i := by
|
||||
refine (l.prop.1 (l.1.getDual i) i ?_).symm
|
||||
simp [getDualProp]
|
||||
apply And.intro
|
||||
exact Subtype.coe_ne_coe.mpr (l.1.getDual_neq_self i).symm
|
||||
exact (l.1.getDual_id i).symm
|
||||
|
||||
lemma contrPairSet_fst_eq_dual_snd (x : l.1.contrPairSet) : x.1.1 = l.1.getDual x.1.2 :=
|
||||
(l.prop.1 (x.1.2) x.1.1 (And.intro (Fin.ne_of_gt x.2.1) x.2.2.symm))
|
||||
|
||||
lemma contrPairSet_snd_eq_dual_fst (x : l.1.contrPairSet) : x.1.2 = l.1.getDual x.1.1 := by
|
||||
rw [contrPairSet_fst_eq_dual_snd, getDual_getDual]
|
||||
|
||||
lemma contrPairSet_dual_snd_lt_self (x : l.1.contrPairSet) :
|
||||
(l.1.getDual x.1.2).1 < x.1.2.1 := by
|
||||
rw [← l.contrPairSet_fst_eq_dual_snd]
|
||||
exact x.2.1
|
||||
|
||||
/-- An equivalence between two coppies of `𝓒.contrPairSet s` and `𝓒.contrSubtype s`.
|
||||
This equivalence exists due to the ordering on pairs in `𝓒.contrPairSet s`. -/
|
||||
def contrPairEquiv : l.1.contrPairSet ⊕ l.1.contrPairSet ≃ l.1.contrSubtype where
|
||||
toFun x :=
|
||||
match x with
|
||||
| Sum.inl p => p.1.2
|
||||
| Sum.inr p => p.1.1
|
||||
invFun x :=
|
||||
if h : (l.1.getDual x).1 < x.1 then
|
||||
Sum.inl ⟨(l.1.getDual x, x), l.1.getDual_lt_self_mem_contrPairSet h⟩
|
||||
else
|
||||
Sum.inr ⟨(x, l.1.getDual x), l.1.getDual_not_lt_self_mem_contrPairSet h⟩
|
||||
left_inv x := by
|
||||
match x with
|
||||
| Sum.inl x =>
|
||||
simp only [Subtype.coe_lt_coe]
|
||||
rw [dif_pos]
|
||||
simp [← l.contrPairSet_fst_eq_dual_snd]
|
||||
exact l.contrPairSet_dual_snd_lt_self _
|
||||
| Sum.inr x =>
|
||||
simp only [Subtype.coe_lt_coe]
|
||||
rw [dif_neg]
|
||||
simp only [← l.contrPairSet_snd_eq_dual_fst, Prod.mk.eta, Subtype.coe_eta]
|
||||
rw [← l.contrPairSet_snd_eq_dual_fst]
|
||||
have h1 := x.2.1
|
||||
simp only [not_lt, ge_iff_le]
|
||||
exact le_of_lt h1
|
||||
right_inv x := by
|
||||
by_cases h1 : (l.1.getDual x).1 < x.1
|
||||
simp only [h1, ↓reduceDIte]
|
||||
simp only [h1, ↓reduceDIte]
|
||||
|
||||
@[simp]
|
||||
lemma contrPairEquiv_apply_inr (x : l.1.contrPairSet) : l.contrPairEquiv (Sum.inr x) = x.1.1 := by
|
||||
simp [contrPairEquiv]
|
||||
|
||||
@[simp]
|
||||
lemma contrPairEquiv_apply_inl(x : l.1.contrPairSet) : l.contrPairEquiv (Sum.inl x) = x.1.2 := by
|
||||
simp [contrPairEquiv]
|
||||
|
||||
/-- An equivalence between `Fin s.length` and
|
||||
`(𝓒.contrPairSet s ⊕ 𝓒.contrPairSet s) ⊕ Fin (𝓒.noContrFinset s).card`, which
|
||||
can be used for contractions. -/
|
||||
def splitContr : Fin l.1.length ≃
|
||||
(l.1.contrPairSet ⊕ l.1.contrPairSet) ⊕ Fin (l.1.noContrFinset).card :=
|
||||
(Equiv.sumCompl l.1.NoContr).symm.trans <|
|
||||
(Equiv.sumComm { i // l.1.NoContr i} { i // ¬ l.1.NoContr i}).trans <|
|
||||
Equiv.sumCongr l.contrPairEquiv.symm l.1.noContrSubtypeEquiv
|
||||
|
||||
lemma splitContr_map :
|
||||
l.1.colorMap ∘ l.splitContr.symm ∘ Sum.inl ∘ Sum.inl =
|
||||
𝓒.τ ∘ l.1.colorMap ∘ l.splitContr.symm ∘ Sum.inl ∘ Sum.inr := by
|
||||
funext x
|
||||
simp [splitContr, contrPairEquiv_apply_inr]
|
||||
erw [contrPairEquiv_apply_inr, contrPairEquiv_apply_inl]
|
||||
rw [contrPairSet_fst_eq_dual_snd _ _]
|
||||
exact l.prop.2 _
|
||||
|
||||
/-!
|
||||
|
||||
## The contracted index list
|
||||
|
||||
-/
|
||||
|
||||
/-- The contracted index list as a `IndexListColor`. -/
|
||||
def contr : IndexListColor 𝓒 :=
|
||||
⟨l.1.contrIndexList, indexListColorProp_of_hasNoContr l.1.contrIndexList_hasNoContr⟩
|
||||
|
||||
/-!
|
||||
|
||||
## Equivalence relation on IndexListColor
|
||||
|
||||
-/
|
||||
|
||||
/-- Two index lists are related if there contracted lists have the same id's for indices,
|
||||
and the color of indices with the same id sit are the same.
|
||||
This will allow us to add and compare tensors. -/
|
||||
def rel (s1 s2 : IndexListColor 𝓒) : Prop :=
|
||||
List.Perm (s1.contr.1.map Index.id) (s2.contr.1.map Index.id)
|
||||
∧ ∀ (l1 : s1.contr.1.toPosFinset)
|
||||
(l2 : s2.contr.1.toPosFinset),
|
||||
l1.1.2.id = l2.1.2.id → l1.1.2.toColor = l2.1.2.toColor
|
||||
|
||||
/-! TODO: Show that `rel` is indeed an equivalence relation. -/
|
||||
|
||||
/-!
|
||||
|
||||
## Appending two IndexListColor
|
||||
|
||||
-/
|
||||
|
||||
def append (s1 s2 : IndexListColor 𝓒) (h : IndexListColorProp 𝓒 (s1.1 ++ s2.1)) :
|
||||
IndexListColor 𝓒 := ⟨s1.1 ++ s2.1, h⟩
|
||||
|
||||
@[simp]
|
||||
lemma append_length {s1 s2 : IndexListColor 𝓒} (h : IndexListColorProp 𝓒 (s1.1 ++ s2.1))
|
||||
(h1 : n = s1.1.length) (h2 : m = s2.1.length) :
|
||||
n + m = (append s1 s2 h).1.length := by
|
||||
erw [List.length_append]
|
||||
simp only [h1, h2]
|
||||
|
||||
end IndexListColor
|
||||
|
||||
end IndexNotation
|
||||
244
HepLean/SpaceTime/LorentzTensor/IndexNotation/IndexString.lean
Normal file
244
HepLean/SpaceTime/LorentzTensor/IndexNotation/IndexString.lean
Normal file
|
|
@ -0,0 +1,244 @@
|
|||
/-
|
||||
Copyright (c) 2024 Joseph Tooby-Smith. All rights reserved.
|
||||
Released under Apache 2.0 license as described in the file LICENSE.
|
||||
Authors: Joseph Tooby-Smith
|
||||
-/
|
||||
import HepLean.SpaceTime.LorentzTensor.IndexNotation.Basic
|
||||
/-!
|
||||
|
||||
# Strings of indices
|
||||
|
||||
A string of indices e.g. `ᵘ¹²ᵤ₄₃` is the structure we usually see
|
||||
following a tensor symbol in index notation.
|
||||
|
||||
This file defines such an index string, and from it constructs a list of indices.
|
||||
|
||||
-/
|
||||
|
||||
open Lean
|
||||
open String
|
||||
|
||||
namespace IndexNotation
|
||||
|
||||
variable (X : Type) [IndexNotation X] [Fintype X] [DecidableEq X]
|
||||
|
||||
/-!
|
||||
|
||||
## Lists of characters forming a string of indices.
|
||||
|
||||
-/
|
||||
|
||||
/-- A lemma used to show terminiation of recursive definitions which follow.
|
||||
It says that the length of `List.dropWhile _ l.tail` is less then the length of
|
||||
`l` when `l` is non-empty. -/
|
||||
lemma dropWhile_isIndexSpecifier_length_lt (l : List Char) (hl : l ≠ []) :
|
||||
(List.dropWhile (fun c => !isNotationChar X c) l.tail).length < l.length := by
|
||||
let ld := l.tail.dropWhile (fun c => ¬ isNotationChar X c)
|
||||
let lt := l.tail.takeWhile (fun c => ¬ isNotationChar X c)
|
||||
simp only [gt_iff_lt]
|
||||
have h2 : lt ++ ld = l.tail := by
|
||||
exact List.takeWhile_append_dropWhile _ _
|
||||
have h3 := congrArg List.length h2
|
||||
rw [List.length_append] at h3
|
||||
have h4 : l.length ≠ 0 := by
|
||||
simp_all only [ne_eq, Bool.not_eq_true, Bool.decide_eq_false, List.takeWhile_append_dropWhile,
|
||||
List.length_tail, List.length_eq_zero, not_false_eq_true]
|
||||
have h5 : l.tail.length < l.length := by
|
||||
rw [List.length_tail]
|
||||
omega
|
||||
have h6 : ld.length < l.length := by
|
||||
omega
|
||||
simpa [ld] using h6
|
||||
|
||||
/-- The proposition for a list of characters to be an index string. -/
|
||||
def listCharIndexString (l : List Char) : Prop :=
|
||||
if h : l = [] then True
|
||||
else
|
||||
let sfst := l.head h
|
||||
if ¬ isNotationChar X sfst then False
|
||||
else
|
||||
let lt := l.tail.takeWhile (fun c => ¬ isNotationChar X c)
|
||||
let ld := l.tail.dropWhile (fun c => ¬ isNotationChar X c)
|
||||
if ¬ listCharIndexTail sfst lt then False
|
||||
else listCharIndexString ld
|
||||
termination_by l.length
|
||||
decreasing_by
|
||||
simpa [ld, InvImage] using dropWhile_isIndexSpecifier_length_lt X l h
|
||||
|
||||
/-- A bool version of `listCharIndexString` for computation. -/
|
||||
def listCharIndexStringBool (l : List Char) : Bool :=
|
||||
if h : l = [] then true
|
||||
else
|
||||
let sfst := l.head h
|
||||
if ¬ isNotationChar X sfst then false
|
||||
else
|
||||
let lt := l.tail.takeWhile (fun c => ¬ isNotationChar X c)
|
||||
let ld := l.tail.dropWhile (fun c => ¬ isNotationChar X c)
|
||||
if ¬ listCharIndexTail sfst lt then false
|
||||
else listCharIndexStringBool ld
|
||||
termination_by l.length
|
||||
decreasing_by
|
||||
simpa [ld, InvImage] using dropWhile_isIndexSpecifier_length_lt X l h
|
||||
|
||||
lemma listCharIndexString_iff (l : List Char) : listCharIndexString X l
|
||||
↔ (if h : l = [] then True else
|
||||
let sfst := l.head h
|
||||
if ¬ isNotationChar X sfst then False
|
||||
else
|
||||
let lt := l.tail.takeWhile (fun c => ¬ isNotationChar X c)
|
||||
let ld := l.tail.dropWhile (fun c => ¬ isNotationChar X c)
|
||||
if ¬ listCharIndexTail sfst lt then False
|
||||
else listCharIndexString X ld) := by
|
||||
rw [listCharIndexString]
|
||||
|
||||
lemma listCharIndexString_iff_bool (l : List Char) :
|
||||
listCharIndexString X l ↔ listCharIndexStringBool X l = true := by
|
||||
rw [listCharIndexString, listCharIndexStringBool]
|
||||
by_cases h : l = []
|
||||
simp [h]
|
||||
simp [h]
|
||||
intro _ _
|
||||
exact listCharIndexString_iff_bool _
|
||||
termination_by l.length
|
||||
decreasing_by
|
||||
simpa [InvImage] using dropWhile_isIndexSpecifier_length_lt X l h
|
||||
|
||||
instance : Decidable (listCharIndexString X l) :=
|
||||
@decidable_of_decidable_of_iff _ _
|
||||
((listCharIndexStringBool X l).decEq true)
|
||||
(listCharIndexString_iff_bool X l).symm
|
||||
|
||||
/-!
|
||||
|
||||
## Returning the chars of first index from chars of string of indices.
|
||||
|
||||
In particular from a list of characters which form an index string,
|
||||
to a list of characters which forms an index.
|
||||
|
||||
-/
|
||||
|
||||
/-- If a list of characters corresponds to an index string, then its head is an
|
||||
index specifier. -/
|
||||
lemma listCharIndexString_head_isIndexSpecifier (l : List Char) (h : listCharIndexString X l)
|
||||
(hl : l ≠ []) : isNotationChar X (l.head hl) := by
|
||||
by_contra
|
||||
rw [listCharIndexString] at h
|
||||
simp_all only [↓reduceDIte, Bool.false_eq_true, not_false_eq_true, ↓reduceIte]
|
||||
|
||||
/-- The tail of the first index in a list of characters corresponds to an index string
|
||||
(junk on other lists). -/
|
||||
def listCharIndexStringHeadIndexTail (l : List Char) : List Char :=
|
||||
l.tail.takeWhile (fun c => ¬ isNotationChar X c)
|
||||
|
||||
/-- The tail of the first index in a list of characters corresponds to an index string
|
||||
is the tail of a list of characters corresponding to an index specified by the head. -/
|
||||
lemma listCharIndexStringHeadIndexTail_listCharIndexTail (l : List Char)
|
||||
(h : listCharIndexString X l) (hl : l ≠ []) :
|
||||
listCharIndexTail (l.head hl) (listCharIndexStringHeadIndexTail X l) := by
|
||||
by_contra
|
||||
have h1 := listCharIndexString_head_isIndexSpecifier X l h hl
|
||||
rw [listCharIndexString] at h
|
||||
simp_all only [not_true_eq_false, Bool.not_eq_true, Bool.decide_eq_false, ite_not, if_false_right,
|
||||
ite_false, dite_false]
|
||||
obtain ⟨left, _⟩ := h
|
||||
rename_i x _
|
||||
simp [listCharIndexStringHeadIndexTail] at x
|
||||
simp_all only [Bool.false_eq_true]
|
||||
|
||||
/-- The first list of characters which form a index, from a list of characters
|
||||
which form a string of indices. -/
|
||||
def listCharIndexStringHeadIndex (l : List Char) : List Char :=
|
||||
if h : l = [] then []
|
||||
else l.head h :: listCharIndexStringHeadIndexTail X l
|
||||
|
||||
lemma listCharIndexStringHeadIndex_listCharIndex (l : List Char) (h : listCharIndexString X l) :
|
||||
listCharIndex X (listCharIndexStringHeadIndex X l) := by
|
||||
by_cases h1 : l = []
|
||||
· subst h1
|
||||
simp [listCharIndex, listCharIndexStringHeadIndex]
|
||||
· simp [listCharIndexStringHeadIndex, listCharIndex, h1]
|
||||
apply And.intro
|
||||
exact listCharIndexString_head_isIndexSpecifier X l h h1
|
||||
exact listCharIndexStringHeadIndexTail_listCharIndexTail X l h h1
|
||||
|
||||
/-!
|
||||
|
||||
## Dropping chars of first index from chars of string of indices.
|
||||
|
||||
-/
|
||||
|
||||
/-- The list of characters obtained by dropping the first block which
|
||||
corresponds to an index. -/
|
||||
def listCharIndexStringDropHeadIndex (l : List Char) : List Char :=
|
||||
l.tail.dropWhile (fun c => ¬ isNotationChar X c)
|
||||
|
||||
lemma listCharIndexStringDropHeadIndex_listCharIndexString (l : List Char)
|
||||
(h : listCharIndexString X l) :
|
||||
listCharIndexString X (listCharIndexStringDropHeadIndex X l) := by
|
||||
by_cases h1 : l = []
|
||||
· subst h1
|
||||
simp [listCharIndexStringDropHeadIndex, listCharIndexString]
|
||||
· simp [listCharIndexStringDropHeadIndex, h1]
|
||||
rw [listCharIndexString] at h
|
||||
simp_all only [↓reduceDIte, Bool.not_eq_true, Bool.decide_eq_false, ite_not, if_false_right,
|
||||
if_false_left, Bool.not_eq_false]
|
||||
|
||||
/-!
|
||||
|
||||
## Chars of all indices from char of string of indices
|
||||
|
||||
-/
|
||||
|
||||
/-- Given a list list of characters corresponding to an index string, the list
|
||||
of lists of characters which correspond to an index and are non-zero corresponding
|
||||
to that index string. -/
|
||||
def listCharIndexStringTolistCharIndex (l : List Char) (h : listCharIndexString X l) :
|
||||
List ({lI : List Char // listCharIndex X lI ∧ lI ≠ []}) :=
|
||||
if hl : l = [] then [] else
|
||||
⟨listCharIndexStringHeadIndex X l, by
|
||||
apply And.intro (listCharIndexStringHeadIndex_listCharIndex X l h)
|
||||
simp [listCharIndexStringHeadIndex]
|
||||
exact hl⟩ ::
|
||||
(listCharIndexStringTolistCharIndex (listCharIndexStringDropHeadIndex X l)
|
||||
(listCharIndexStringDropHeadIndex_listCharIndexString X l h))
|
||||
termination_by l.length
|
||||
decreasing_by
|
||||
rename_i h1
|
||||
simpa [InvImage, listCharIndexStringDropHeadIndex] using
|
||||
dropWhile_isIndexSpecifier_length_lt X l hl
|
||||
|
||||
/-!
|
||||
|
||||
## The definition of an index string
|
||||
|
||||
-/
|
||||
|
||||
/-- A string of indices to be associated with a tensor. For example, `ᵘ⁰ᵤ₂₆₀ᵘ³`. -/
|
||||
def IndexString : Type := {s : String // listCharIndexStringBool X s.toList = true}
|
||||
|
||||
namespace IndexString
|
||||
|
||||
/-!
|
||||
|
||||
## Constructing a list of indices from an index string
|
||||
|
||||
-/
|
||||
|
||||
variable {X : Type} [IndexNotation X] [Fintype X] [DecidableEq X]
|
||||
|
||||
/-- The character list associated with a index string. -/
|
||||
def toCharList (s : IndexString X) : List Char := s.val.toList
|
||||
|
||||
/-- The char list of an index string satisfies `listCharIndexString`. -/
|
||||
lemma listCharIndexString (s : IndexString X) : listCharIndexString X s.toCharList := by
|
||||
rw [listCharIndexString_iff_bool]
|
||||
exact s.prop
|
||||
|
||||
/-- The indices associated to an index string. -/
|
||||
def toIndexList (s : IndexString X) : IndexList X :=
|
||||
(listCharIndexStringTolistCharIndex X s.toCharList (listCharIndexString s)).map
|
||||
fun x => Index.ofCharList x.1 x.2
|
||||
|
||||
end IndexString
|
||||
|
||||
end IndexNotation
|
||||
|
|
@ -0,0 +1,45 @@
|
|||
/-
|
||||
Copyright (c) 2024 Joseph Tooby-Smith. All rights reserved.
|
||||
Released under Apache 2.0 license as described in the file LICENSE.
|
||||
Authors: Joseph Tooby-Smith
|
||||
-/
|
||||
import HepLean.SpaceTime.LorentzTensor.IndexNotation.IndexListColor
|
||||
import HepLean.SpaceTime.LorentzTensor.Basic
|
||||
/-!
|
||||
|
||||
# The structure of a tensor with a string of indices
|
||||
|
||||
-/
|
||||
|
||||
namespace TensorStructure
|
||||
open TensorColor
|
||||
open IndexNotation
|
||||
|
||||
variable {R : Type} [CommSemiring R] (𝓣 : TensorStructure R)
|
||||
|
||||
variable {d : ℕ} {X Y Y' Z W : Type} [Fintype X] [DecidableEq X] [Fintype Y] [DecidableEq Y]
|
||||
[Fintype Y'] [DecidableEq Y'] [Fintype Z] [DecidableEq Z] [Fintype W] [DecidableEq W]
|
||||
{cX cX2 : X → 𝓣.Color} {cY : Y → 𝓣.Color} {cZ : Z → 𝓣.Color}
|
||||
{cW : W → 𝓣.Color} {cY' : Y' → 𝓣.Color} {μ ν η : 𝓣.Color}
|
||||
|
||||
variable [IndexNotation 𝓣.Color] [Fintype 𝓣.Color] [DecidableEq 𝓣.Color]
|
||||
|
||||
structure TensorIndex (cn : Fin n → 𝓣.Color) where
|
||||
tensor : 𝓣.Tensor cn
|
||||
index : IndexListColor 𝓣.toTensorColor
|
||||
nat_eq : n = index.1.length
|
||||
quot_eq : 𝓣.colorQuot ∘ index.1.colorMap ∘ Fin.cast nat_eq = 𝓣.colorQuot ∘ cn
|
||||
|
||||
namespace TensorIndex
|
||||
|
||||
variable {𝓣 : TensorStructure R} [IndexNotation 𝓣.Color] [Fintype 𝓣.Color] [DecidableEq 𝓣.Color]
|
||||
variable {n m : ℕ} {cn : Fin n → 𝓣.Color} {cm : Fin m → 𝓣.Color} (T : TensorIndex 𝓣 cn)
|
||||
section noncomputable
|
||||
|
||||
def smul (r : R) : TensorIndex 𝓣 cn := ⟨r • T.tensor, T.index, T.nat_eq, T.quot_eq⟩
|
||||
|
||||
end
|
||||
|
||||
end TensorIndex
|
||||
|
||||
end TensorStructure
|
||||
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Add table
Add a link
Reference in a new issue