docs: Docs for Wick contractions

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jstoobysmith 2025-02-07 06:58:41 +00:00
parent ce9668a3cd
commit c9607c459f
13 changed files with 123 additions and 64 deletions

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@ -118,6 +118,9 @@ lemma crPart_mul_normalOrder (φ : 𝓕.FieldOp) (a : 𝓕.FieldOpAlgebra) :
-/ -/
/-- For a field specfication `𝓕`, and `a` and `b` in `𝓕.FieldOpAlgebra` the normal ordering
of the super commutator of `a` and `b` vanishes. I.e. `𝓝([a,b]ₛ) = 0`. -/
@[simp] @[simp]
lemma normalOrder_superCommute_eq_zero (a b : 𝓕.FieldOpAlgebra) : lemma normalOrder_superCommute_eq_zero (a b : 𝓕.FieldOpAlgebra) :
𝓝([a, b]ₛ) = 0 := by 𝓝([a, b]ₛ) = 0 := by
@ -226,7 +229,7 @@ The proof of this result ultimetly goes as follows
- The definition of `normalOrder` is used to rewrite `𝓝(φ₀…φₙ)` as a scalar multiple of - The definition of `normalOrder` is used to rewrite `𝓝(φ₀…φₙ)` as a scalar multiple of
a `ofCrAnList φsn` where `φsn` is the normal ordering of `φ₀…φₙ`. a `ofCrAnList φsn` where `φsn` is the normal ordering of `φ₀…φₙ`.
- `superCommuteF_ofCrAnListF_ofCrAnListF_eq_sum` is used to rewrite the super commutator of `φ` - `superCommuteF_ofCrAnListF_ofCrAnListF_eq_sum` is used to rewrite the super commutator of `φ`
(considered as a list with one lement) with (considered as a list with one element) with
`ofCrAnList φsn` as a sum of supercommutors, one for each element of `φsn`. `ofCrAnList φsn` as a sum of supercommutors, one for each element of `φsn`.
- The fact that super-commutors are in the center of `𝓕.FieldOpAlgebra` is used to rearange terms. - The fact that super-commutors are in the center of `𝓕.FieldOpAlgebra` is used to rearange terms.
- Properties of ordered lists, and `normalOrderSign_eraseIdx` is then used to complete the proof. - Properties of ordered lists, and `normalOrderSign_eraseIdx` is then used to complete the proof.

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@ -25,10 +25,14 @@ variable {𝓕 : FieldSpecification}
-/ -/
/-- /-- For a list `φs = φ₀…φₙ` of `𝓕.FieldOp`, a Wick contraction `φsΛ` of `φs`, an element `φ` of
Let `c` be a Wick Contraction for `φs := φ₀φ₁…φₙ`. `𝓕.FieldOp`, and a `i ≤ φs.length` the following relation holds
We have (roughly) `𝓝ᶠ([φsΛ ↩Λ φ i none]ᵘᶜ) = s • 𝓝ᶠ(φ :: [φsΛ]ᵘᶜ)`
Where `s` is the exchange sign for `φ` and the uncontracted fields in `φ₀φ₁…φᵢ₋₁`. `𝓝([φsΛ ↩Λ φ i none]ᵘᶜ) = s • 𝓝(φ :: [φsΛ]ᵘᶜ)`
where `s` is the exchange sign for `φ` and the uncontracted fields in `φ₀…φᵢ₋₁`.
The prove of this result ultimately a consequence of `normalOrder_superCommute_eq_zero`.
-/ -/
lemma normalOrder_uncontracted_none (φ : 𝓕.FieldOp) (φs : List 𝓕.FieldOp) lemma normalOrder_uncontracted_none (φ : 𝓕.FieldOp) (φs : List 𝓕.FieldOp)
(i : Fin φs.length.succ) (φsΛ : WickContraction φs.length) : (i : Fin φs.length.succ) (φsΛ : WickContraction φs.length) :
@ -95,10 +99,12 @@ lemma normalOrder_uncontracted_none (φ : 𝓕.FieldOp) (φs : List 𝓕.FieldOp
rw [insertAndContract_uncontractedList_none_map] rw [insertAndContract_uncontractedList_none_map]
/-- /--
Let `c` be a Wick Contraction for `φ₀φ₁…φₙ`. For a list `φs = φ₀…φₙ` of `𝓕.FieldOp`, a Wick contraction `φsΛ` of `φs`, an element `φ` of
We have (roughly) `N(c ↩Λ φ i k).uncontractedList` `𝓕.FieldOp`, a `i ≤ φs.length` and a `k` in `φsΛ.uncontracted`, then
is equal to `N((c.uncontractedList).eraseIdx k')` `𝓝([φsΛ ↩Λ φ i none]ᵘᶜ)` is equal to the normal ordering of `[φsΛ]ᵘᶜ` with the `FieldOp`
where `k'` is the position in `c.uncontractedList` corresponding to `k`. corresponding to `k` removed.
The proof of this result ultimately a consequence of definitions.
-/ -/
lemma normalOrder_uncontracted_some (φ : 𝓕.FieldOp) (φs : List 𝓕.FieldOp) lemma normalOrder_uncontracted_some (φ : 𝓕.FieldOp) (φs : List 𝓕.FieldOp)
(i : Fin φs.length.succ) (φsΛ : WickContraction φs.length) (k : φsΛ.uncontracted) : (i : Fin φs.length.succ) (φsΛ : WickContraction φs.length) (k : φsΛ.uncontracted) :

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@ -14,13 +14,18 @@ open FieldSpecification
variable {𝓕 : FieldSpecification} variable {𝓕 : FieldSpecification}
/-- /--
Given a natural number `n` corresponding to the number of fields, a Wick contraction Given a natural number `n`, which will correspond to the number of fields needing
is a finite set of pairs of `Fin n`, such that no element of `Fin n` occurs in more then one pair. contracting, a Wick contraction
is a finite set of pairs of `Fin n` (numbers `0`, …, `n-1`), such that no
element of `Fin n` occurs in more then one pair. The pairs are the positions of fields we
'contract' together.
For example for `n = 3` there are `4` Wick contractions: For example for `n = 3` there are `4` Wick contractions:
- `∅`, corresponding to the case where no fields are contracted. - `∅`, corresponding to the case where no fields are contracted.
- `{{0, 1}}`, corresponding to the case where the field at position `0` and `1` are contracted. - `{{0, 1}}`, corresponding to the case where the field at position `0` and `1` are contracted.
- `{{0, 2}}`, corresponding to the case where the field at position `0` and `2` are contracted. - `{{0, 2}}`, corresponding to the case where the field at position `0` and `2` are contracted.
- `{{1, 2}}`, corresponding to the case where the field at position `1` and `2` are contracted. - `{{1, 2}}`, corresponding to the case where the field at position `1` and `2` are contracted.
For `n=4` some possible Wick contractions are For `n=4` some possible Wick contractions are
- `∅`, corresponding to the case where no fields are contracted. - `∅`, corresponding to the case where no fields are contracted.
- `{{0, 1}, {2, 3}}`, corresponding to the case where the field at position `0` and `1` are - `{{0, 1}, {2, 3}}`, corresponding to the case where the field at position `0` and `1` are
@ -37,6 +42,12 @@ namespace WickContraction
variable {n : } (c : WickContraction n) variable {n : } (c : WickContraction n)
open HepLean.List open HepLean.List
remark contraction_notation := "Given a field specification `𝓕`, and a list `φs`
of `𝓕.FieldOp`, a Wick contraction of `φs` will mean a Wick contraction in
`WickContraction φs.length`. The notation `φsΛ` will be used for such contractions.
The terminology that `φsΛ` contracts pairs within of `φs` will also be used, even though
`φsΛ` is really contains positions of `φs`."
/-- Wick contractions are decidable. -/ /-- Wick contractions are decidable. -/
instance : DecidableEq (WickContraction n) := Subtype.instDecidableEq instance : DecidableEq (WickContraction n) := Subtype.instDecidableEq
@ -520,8 +531,11 @@ lemma prod_finset_eq_mul_fst_snd (c : WickContraction n) (a : c.1)
rw [← (c.contractEquivFinTwo a).symm.prod_comp] rw [← (c.contractEquivFinTwo a).symm.prod_comp]
simp [contractEquivFinTwo] simp [contractEquivFinTwo]
/-- A Wick contraction associated with a list of states is said to be `GradingCompliant` if in any /-- For a field specification `𝓕`, `φs` a list of `𝓕.FieldOp` and a Wick contraction
contracted pair of states they are either both fermionic or both bosonic. -/ `φsΛ` of `φs`, the Wick contraction `φsΛ` is said to be `GradingCompliant` if
for every pair in `φsΛ` the contracted fields are either both `fermionic` or both `bosonic`.
I.e. in a `GradingCompliant` Wick contraction no contractions occur between `fermionic` and
`bosonic` fields. -/
def GradingCompliant (φs : List 𝓕.FieldOp) (φsΛ : WickContraction φs.length) := def GradingCompliant (φs : List 𝓕.FieldOp) (φsΛ : WickContraction φs.length) :=
∀ (a : φsΛ.1), (𝓕 |>ₛ φs[φsΛ.fstFieldOfContract a]) = (𝓕 |>ₛ φs[φsΛ.sndFieldOfContract a]) ∀ (a : φsΛ.1), (𝓕 |>ₛ φs[φsΛ.fstFieldOfContract a]) = (𝓕 |>ₛ φs[φsΛ.sndFieldOfContract a])

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@ -236,9 +236,9 @@ def cardFun :
| 1 => 1 | 1 => 1
| Nat.succ (Nat.succ n) => cardFun (Nat.succ n) + (n + 1) * cardFun n | Nat.succ (Nat.succ n) => cardFun (Nat.succ n) + (n + 1) * cardFun n
/-- The number of Wick contractions for `n : ` fields, i.e. the cardinality of /-- The number of Wick contractions in `WickContraction n` is equal to the terms in
`WickContraction n`, is equal to the terms in Online Encyclopedia of Integer Sequences (OEIS) A000085. That is:
Online Encyclopedia of Integer Sequences (OEIS) A000085. -/ 1, 1, 2, 4, 10, 26, 76, 232, 764, 2620, 9496, ... -/
theorem card_eq_cardFun : (n : ) → Fintype.card (WickContraction n) = cardFun n theorem card_eq_cardFun : (n : ) → Fintype.card (WickContraction n) = cardFun n
| 0 => by decide | 0 => by decide
| 1 => by decide | 1 => by decide

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@ -24,15 +24,19 @@ open HepLean.Fin
-/ -/
/-- Given a Wick contraction `φsΛ` associated to a list `φs`, /-- Given a Wick contraction `φsΛ` for a list `φs` of `𝓕.FieldOp`,
a position `i : Fin φs.lengthsucc`, an element `φ`, and an optional uncontracted element a `𝓕.FieldOp` `φ`, an `i ≤ φs.length` and a `j` which is either `none` or
`j : Option (φsΛ.uncontracted)` of `φsΛ`. some element of `φsΛ.uncontracted`, the new Wick contraction
The Wick contraction `φsΛ.insertAndContract φ i j` is defined to be the Wick contraction `φsΛ.insertAndContract φ i j` is defined by inserting `φ` into `φs` after
associated with `(φs.insertIdx i φ)` formed by 'inserting' `φ` into `φs` after the first `i` the first `i`-elements and moving the values representing the contracted pairs in `φsΛ`
elements and contracting `φ` optionally with `j`. accordingly.
If `j` is not `none`, but rather `some j`, to this contraction is added the contraction
of `φ` (at position `i`) with the new position of `j` after `φ` is added.
The notation `φsΛ ↩Λ φ i j` is used to denote `φsΛ.insertAndContract φ i j`. Thus, In other words, `φsΛ.insertAndContract φ i j` is formed by adding `φ` to `φs` at position `i`,
`φsΛ ↩Λ φ i none` indicates the case when we insert `φ` into `φs` but do not contract it. -/ and contracting `φ` with the field orginally at position `j` if `j` is not none.
The notation `φsΛ ↩Λ φ i j` is used to denote `φsΛ.insertAndContract φ i j`. -/
def insertAndContract {φs : List 𝓕.FieldOp} (φ : 𝓕.FieldOp) (φsΛ : WickContraction φs.length) def insertAndContract {φs : List 𝓕.FieldOp} (φ : 𝓕.FieldOp) (φsΛ : WickContraction φs.length)
(i : Fin φs.length.succ) (j : Option φsΛ.uncontracted) : (i : Fin φs.length.succ) (j : Option φsΛ.uncontracted) :
WickContraction (φs.insertIdx i φ).length := WickContraction (φs.insertIdx i φ).length :=

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@ -23,9 +23,9 @@ variable {n : } (c : WickContraction n)
open HepLean.List open HepLean.List
open FieldOpAlgebra open FieldOpAlgebra
/-- Given a Wick contraction `φsΛ` on `φs` and a Wick contraction `φsucΛ` on the uncontracted fields /-- Given a list `φs` of `𝓕.FieldOp`, a Wick contraction `φsΛ` of `φs` and a Wick contraction
within `φsΛ`, a Wick contraction on `φs`consisting of the contractins in `φsΛ` and `φsucΛ` of `[φsΛ]ᵘᶜ`, `join φsΛ φsucΛ` is defined as the Wick contraction of `φs` consisting of
the contractions in `φsucΛ`. -/ the contractions in `φsΛ` and those in `φsucΛ`. -/
def join {φs : List 𝓕.FieldOp} (φsΛ : WickContraction φs.length) def join {φs : List 𝓕.FieldOp} (φsΛ : WickContraction φs.length)
(φsucΛ : WickContraction [φsΛ]ᵘᶜ.length) : WickContraction φs.length := (φsucΛ : WickContraction [φsΛ]ᵘᶜ.length) : WickContraction φs.length :=
⟨φsΛ.1 φsucΛ.1.map (Finset.mapEmbedding uncontractedListEmd).toEmbedding, by ⟨φsΛ.1 φsucΛ.1.map (Finset.mapEmbedding uncontractedListEmd).toEmbedding, by

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@ -28,10 +28,11 @@ def signFinset (c : WickContraction n) (i1 i2 : Fin n) : Finset (Fin n) :=
Finset.univ.filter (fun i => i1 < i ∧ i < i2 ∧ Finset.univ.filter (fun i => i1 < i ∧ i < i2 ∧
(c.getDual? i = none ∀ (h : (c.getDual? i).isSome), i1 < (c.getDual? i).get h)) (c.getDual? i = none ∀ (h : (c.getDual? i).isSome), i1 < (c.getDual? i).get h))
/-- Given a Wick contraction `φsΛ` associated with a list of states `φs` /-- For a list `φs` of `𝓕.FieldOp`, and a Wick contraction `φsΛ` of `φs`,
the sign associated with `φsΛ` is the sign corresponding to the number the complex number `φsΛ.sign` is defined to be the sign (`1` or `-1`) corresponding
of fermionic-fermionic exchanges one must do to put elements in contracted pairs to the number of `fermionic`-`fermionic` exchanges that must done to put
of `φsΛ` next to each other. -/ contracted pairs with `φsΛ` next to one another, starting from the contracted pair
whose first element occurs at the left-most position. -/
def sign (φs : List 𝓕.FieldOp) (φsΛ : WickContraction φs.length) : := def sign (φs : List 𝓕.FieldOp) (φsΛ : WickContraction φs.length) : :=
∏ (a : φsΛ.1), 𝓢(𝓕 |>ₛ φs[φsΛ.sndFieldOfContract a], ∏ (a : φsΛ.1), 𝓢(𝓕 |>ₛ φs[φsΛ.sndFieldOfContract a],
𝓕 |>ₛ ⟨φs.get, φsΛ.signFinset (φsΛ.fstFieldOfContract a) (φsΛ.sndFieldOfContract a)⟩) 𝓕 |>ₛ ⟨φs.get, φsΛ.signFinset (φsΛ.fstFieldOfContract a) (φsΛ.sndFieldOfContract a)⟩)

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@ -238,10 +238,14 @@ lemma signInsertNone_eq_filterset (φ : 𝓕.FieldOp) (φs : List 𝓕.FieldOp)
simp [h] simp [h]
· exact hG · exact hG
/-- For `φsΛ` a grading compliant Wick contraction, and `i : Fin φs.length.succ` we have /-- For a list `φs = φ₀…φₙ` of `𝓕.FieldOp`, a graded compliant Wick contraction `φsΛ` of `φs`,
an `i ≤ φs.length` and a `φ` in `𝓕.FieldOp`, the following relation holds
`(φsΛ ↩Λ φ i none).sign = s * φsΛ.sign` `(φsΛ ↩Λ φ i none).sign = s * φsΛ.sign`
where `s` is the sign got by moving `φ` through the elements of `φ₀…φᵢ₋₁` which where `s` is the sign got by moving `φ` through the elements of `φ₀…φᵢ₋₁` which
are contracted. -/ are contracted with some element.
The proof of this result involves a careful consideration of the contributions of different
`FieldOp`s in `φs` to the sign of `φsΛ ↩Λ φ i none`. -/
lemma sign_insert_none (φ : 𝓕.FieldOp) (φs : List 𝓕.FieldOp) lemma sign_insert_none (φ : 𝓕.FieldOp) (φs : List 𝓕.FieldOp)
(φsΛ : WickContraction φs.length) (i : Fin φs.length.succ) (hG : GradingCompliant φs φsΛ) : (φsΛ : WickContraction φs.length) (i : Fin φs.length.succ) (hG : GradingCompliant φs φsΛ) :
(φsΛ ↩Λ φ i none).sign = 𝓢(𝓕 |>ₛ φ, 𝓕 |>ₛ ⟨φs.get, Finset.univ.filter (φsΛ ↩Λ φ i none).sign = 𝓢(𝓕 |>ₛ φ, 𝓕 |>ₛ ⟨φs.get, Finset.univ.filter
@ -250,6 +254,11 @@ lemma sign_insert_none (φ : 𝓕.FieldOp) (φs : List 𝓕.FieldOp)
rw [signInsertNone_eq_filterset] rw [signInsertNone_eq_filterset]
exact hG exact hG
/-- For a list `φs = φ₀…φₙ` of `𝓕.FieldOp`, a graded compliant Wick contraction `φsΛ` of `φs`,
and a `φ` in `𝓕.FieldOp`, the following relation holds
`(φsΛ ↩Λ φ 0 none).sign = φsΛ.sign`.
This is a direct corollary of `sign_insert_none`. -/
lemma sign_insert_none_zero (φ : 𝓕.FieldOp) (φs : List 𝓕.FieldOp) lemma sign_insert_none_zero (φ : 𝓕.FieldOp) (φs : List 𝓕.FieldOp)
(φsΛ : WickContraction φs.length) : (φsΛ ↩Λ φ 0 none).sign = φsΛ.sign := by (φsΛ : WickContraction φs.length) : (φsΛ ↩Λ φ 0 none).sign = φsΛ.sign := by
rw [sign_insert_none_eq_signInsertNone_mul_sign] rw [sign_insert_none_eq_signInsertNone_mul_sign]

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@ -855,13 +855,15 @@ lemma signInsertSome_mul_filter_contracted_of_not_lt (φ : 𝓕.FieldOp) (φs :
exact fun h => lt_of_le_of_ne h (Fin.succAbove_ne i ((φsΛ.getDual? j).get hj)) exact fun h => lt_of_le_of_ne h (Fin.succAbove_ne i ((φsΛ.getDual? j).get hj))
/-- /--
For `k < i`, the sign of `φsΛ ↩Λ φ i (some k)` is equal to the product of For a list `φs = φ₀…φₙ` of `𝓕.FieldOp`, a Wick contraction `φsΛ` of `φs`, an element `φ` of
- the sign associated with moving `φ` through the `φsΛ`-uncontracted fields in `φ₀…φₖ`, `𝓕.FieldOp`, a `i ≤ φs.length` and a `k` in `φsΛ.uncontracted` such that `k<i`,
- the sign associated with moving `φ` through the fields in `φ₀…φᵢ₋₁`, the sign of `φsΛ ↩Λ φ i (some k)` is equal to the product of
- the sign associated with moving `φ` through the `φsΛ`-uncontracted `FieldOp` in `φ₀…φₖ`,
- the sign associated with moving `φ` through all `FieldOp` in `φ₀…φᵢ₋₁`,
- the sign of `φsΛ`. - the sign of `φsΛ`.
The proof of this result involves a careful consideration of the contributions of different The proof of this result involves a careful consideration of the contributions of different
fields in `φs` to the sign of `φsΛ ↩Λ φ i (some k)`. `FieldOp` in `φs` to the sign of `φsΛ ↩Λ φ i (some k)`.
-/ -/
lemma sign_insert_some_of_lt (φ : 𝓕.FieldOp) (φs : List 𝓕.FieldOp) lemma sign_insert_some_of_lt (φ : 𝓕.FieldOp) (φs : List 𝓕.FieldOp)
(φsΛ : WickContraction φs.length) (i : Fin φs.length.succ) (k : φsΛ.uncontracted) (φsΛ : WickContraction φs.length) (i : Fin φs.length.succ) (k : φsΛ.uncontracted)
@ -878,13 +880,15 @@ lemma sign_insert_some_of_lt (φ : 𝓕.FieldOp) (φs : List 𝓕.FieldOp)
simp simp
/-- /--
For `i ≤ k`, the sign of `φsΛ ↩Λ φ i (some k)` is equal to the product of For a list `φs = φ₀…φₙ` of `𝓕.FieldOp`, a Wick contraction `φsΛ` of `φs`, an element `φ` of
- the sign associated with moving `φ` through the `φsΛ`-uncontracted fields in `φ₀…φₖ₋₁`, `𝓕.FieldOp`, a `i ≤ φs.length` and a `k` in `φsΛ.uncontracted` such that `i ≤ k`,
- the sign associated with moving `φ` through the fields in `φ₀…φᵢ₋₁`, the sign of `φsΛ ↩Λ φ i (some k)` is equal to the product of
- the sign associated with moving `φ` through the `φsΛ`-uncontracted `FieldOp` in `φ₀…φₖ₋₁`,
- the sign associated with moving `φ` through all the `FieldOp` in `φ₀…φᵢ₋₁`,
- the sign of `φsΛ`. - the sign of `φsΛ`.
The proof of this result involves a careful consideration of the contributions of different The proof of this result involves a careful consideration of the contributions of different
fields in `φs` to the sign of `φsΛ ↩Λ φ i (some k)`. `FieldOp` in `φs` to the sign of `φsΛ ↩Λ φ i (some k)`.
-/ -/
lemma sign_insert_some_of_not_lt (φ : 𝓕.FieldOp) (φs : List 𝓕.FieldOp) lemma sign_insert_some_of_not_lt (φ : 𝓕.FieldOp) (φs : List 𝓕.FieldOp)
(φsΛ : WickContraction φs.length) (i : Fin φs.length.succ) (k : φsΛ.uncontracted) (φsΛ : WickContraction φs.length) (i : Fin φs.length.succ) (k : φsΛ.uncontracted)
@ -900,6 +904,15 @@ lemma sign_insert_some_of_not_lt (φ : 𝓕.FieldOp) (φs : List 𝓕.FieldOp)
rw [mul_comm, ← mul_assoc] rw [mul_comm, ← mul_assoc]
simp simp
/--
For a list `φs = φ₀…φₙ` of `𝓕.FieldOp`, a Wick contraction `φsΛ` of `φs`, an element `φ` of
`𝓕.FieldOp`, and a `k` in `φsΛ.uncontracted`,
the sign of `φsΛ ↩Λ φ 0 (some k)` is equal to the product of
- the sign associated with moving `φ` through the `φsΛ`-uncontracted `FieldOp` in `φ₀…φₖ₋₁`,
- the sign of `φsΛ`.
This is a direct corollary of `sign_insert_some_of_not_lt`.
-/
lemma sign_insert_some_zero (φ : 𝓕.FieldOp) (φs : List 𝓕.FieldOp) lemma sign_insert_some_zero (φ : 𝓕.FieldOp) (φs : List 𝓕.FieldOp)
(φsΛ : WickContraction φs.length) (k : φsΛ.uncontracted) (φsΛ : WickContraction φs.length) (k : φsΛ.uncontracted)
(hn : GradingCompliant φs φsΛ ∧ (𝓕|>ₛφ) = 𝓕|>ₛφs[k.1]) : (hn : GradingCompliant φs φsΛ ∧ (𝓕|>ₛφ) = 𝓕|>ₛφs[k.1]) :

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@ -417,11 +417,13 @@ lemma join_sign_induction {φs : List 𝓕.FieldOp} (φsΛ : WickContraction φs
apply sign_congr apply sign_congr
exact join_uncontractedListGet (singleton hij) φsucΛ' exact join_uncontractedListGet (singleton hij) φsucΛ'
/-- Let `φsΛ` be a grading compliant Wick contraction for `φs` and /-- For a list `φs` of `𝓕.FieldOp`, a grading compliant Wick contraction `φsΛ` of `φs`,
`φsucΛ` a Wick contraction for `[φsΛ]ᵘᶜ`. Then `(join φsΛ φsucΛ).sign = φsΛ.sign * φsucΛ.sign`. and a Wick contraction `φsucΛ` of `[φsΛ]ᵘᶜ`, the following relation holds
`(join φsΛ φsucΛ).sign = φsΛ.sign * φsucΛ.sign`.
This lemma manifests the fact that it does not matter which order contracted pairs are brought In `φsΛ.sign` the sign is determined by starting with the contracted pair
together when defining the sign of a contraction. -/ whose first element occurs at the left-most position. This lemma manifests that
choice does not matter, and that contracted pairs can be brought together in any order. -/
lemma join_sign {φs : List 𝓕.FieldOp} (φsΛ : WickContraction φs.length) lemma join_sign {φs : List 𝓕.FieldOp} (φsΛ : WickContraction φs.length)
(φsucΛ : WickContraction [φsΛ]ᵘᶜ.length) (hc : φsΛ.GradingCompliant) : (φsucΛ : WickContraction [φsΛ]ᵘᶜ.length) (hc : φsΛ.GradingCompliant) :
(join φsΛ φsucΛ).sign = φsΛ.sign * φsucΛ.sign := by (join φsΛ φsucΛ).sign = φsΛ.sign * φsucΛ.sign := by

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@ -16,7 +16,8 @@ namespace WickContraction
variable {n : } (c : WickContraction n) variable {n : } (c : WickContraction n)
open HepLean.List open HepLean.List
/-- Given a Wick contraction, the finset of elements of `Fin n` which are not contracted. -/ /-- For a Wick contraction `c`, `c.uncontracted` is defined as the finset of elements of `Fin n`
which are not in any contracted pair. -/
def uncontracted : Finset (Fin n) := Finset.filter (fun i => c.getDual? i = none) (Finset.univ) def uncontracted : Finset (Fin n) := Finset.filter (fun i => c.getDual? i = none) (Finset.univ)
lemma congr_uncontracted {n m : } (c : WickContraction n) (h : n = m) : lemma congr_uncontracted {n m : } (c : WickContraction n) (h : n = m) :

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@ -314,8 +314,11 @@ lemma take_uncontractedIndexEquiv_symm (k : c.uncontracted) :
-/ -/
/-- Given a Wick Contraction `φsΛ` for a list of states `φs`. The list of uncontracted /-- Given a Wick Contraction `φsΛ` of a list `φs` of `𝓕.FieldOp`. The list
states in `φs`. -/ `φsΛ.uncontractedListGet` of `𝓕.FieldOp` is defined as the list `φs` with
all contracted positions removed, leaving the uncontracted `𝓕.FieldOp`.
The notation `[φsΛ]ᵘᶜ` is used for `φsΛ.uncontractedListGet`. -/
def uncontractedListGet {φs : List 𝓕.FieldOp} (φsΛ : WickContraction φs.length) : def uncontractedListGet {φs : List 𝓕.FieldOp} (φsΛ : WickContraction φs.length) :
List 𝓕.FieldOp := φsΛ.uncontractedList.map φs.get List 𝓕.FieldOp := φsΛ.uncontractedList.map φs.get

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@ -192,30 +192,33 @@ def perturbationTheory : Note where
.name ``FieldSpecification.normalOrderSign_eraseIdx .complete, .name ``FieldSpecification.normalOrderSign_eraseIdx .complete,
.name ``FieldSpecification.FieldOpFreeAlgebra.normalOrderF .complete, .name ``FieldSpecification.FieldOpFreeAlgebra.normalOrderF .complete,
.name ``FieldSpecification.FieldOpAlgebra.normalOrder .complete, .name ``FieldSpecification.FieldOpAlgebra.normalOrder .complete,
.name ``FieldSpecification.FieldOpAlgebra.normalOrder_superCommute_eq_zero .complete,
.name ``FieldSpecification.FieldOpAlgebra.ofCrAnOp_superCommute_normalOrder_ofCrAnList_sum .complete, .name ``FieldSpecification.FieldOpAlgebra.ofCrAnOp_superCommute_normalOrder_ofCrAnList_sum .complete,
.name ``FieldSpecification.FieldOpAlgebra.ofFieldOp_mul_normalOrder_ofFieldOpList_eq_sum .complete, .name ``FieldSpecification.FieldOpAlgebra.ofFieldOp_mul_normalOrder_ofFieldOpList_eq_sum .complete,
.h1 "Wick Contractions", .h1 "Wick Contractions",
.h2 "Definition", .h2 "Definition",
.name ``WickContraction .incomplete, .name ``WickContraction .complete,
.name ``WickContraction.GradingCompliant .incomplete, .name `WickContraction.contraction_notation .complete,
.name ``WickContraction.GradingCompliant .complete,
.h2 "Aside: Cardinality", .h2 "Aside: Cardinality",
.name ``WickContraction.card_eq_cardFun .incomplete, .name ``WickContraction.card_eq_cardFun .complete,
.h2 "Uncontracted elements",
.name ``WickContraction.uncontracted .complete,
.name ``WickContraction.uncontractedListGet .complete,
.h2 "Constructors", .h2 "Constructors",
.p "There are a number of ways to construct a Wick contraction from .name ``WickContraction.insertAndContract .complete,
other Wick contractions or single contractions.", .name ``WickContraction.join .complete,
.name ``WickContraction.insertAndContract .incomplete,
.name ``WickContraction.join .incomplete,
.h2 "Sign", .h2 "Sign",
.name ``WickContraction.sign .incomplete, .name ``WickContraction.sign .complete,
.name ``WickContraction.join_sign .incomplete, .name ``WickContraction.join_sign .complete,
.name ``WickContraction.sign_insert_none .incomplete, .name ``WickContraction.sign_insert_none .complete,
.name ``WickContraction.sign_insert_none_zero .incomplete, .name ``WickContraction.sign_insert_none_zero .complete,
.name ``WickContraction.sign_insert_some_of_not_lt .incomplete, .name ``WickContraction.sign_insert_some_of_not_lt .complete,
.name ``WickContraction.sign_insert_some_of_lt .incomplete, .name ``WickContraction.sign_insert_some_of_lt .complete,
.name ``WickContraction.sign_insert_some_zero .incomplete, .name ``WickContraction.sign_insert_some_zero .complete,
.h2 "Normal order", .h2 "Normal order",
.name ``FieldSpecification.FieldOpAlgebra.normalOrder_uncontracted_none .incomplete, .name ``FieldSpecification.FieldOpAlgebra.normalOrder_uncontracted_none .complete,
.name ``FieldSpecification.FieldOpAlgebra.normalOrder_uncontracted_some .incomplete, .name ``FieldSpecification.FieldOpAlgebra.normalOrder_uncontracted_some .complete,
.h1 "Static contractions", .h1 "Static contractions",
.name ``WickContraction.staticContract .incomplete, .name ``WickContraction.staticContract .incomplete,
.name ``WickContraction.staticContract_insert_some_of_lt .incomplete, .name ``WickContraction.staticContract_insert_some_of_lt .incomplete,