Khovanov homology of classical links

The declarations the status of Tau Ceti's roadmap names as Tau Ceti has them at commit ace60277.

TheoremThe enhanced state sum of a nonempty diagram is (q + q⁻¹) times its Jones polynomial at t ^ (1/2) = -q#

The hypothesis 0 < componentCount says that the diagram is nonempty; it excludes the empty diagram, whose enhanced state sum is 1.

TauCeti.OrientedPDCode.enhancedStateSum_eq_mul_eval₂_jonesPolynomial {n : ℕ}
  (D : TauCeti.OrientedPDCode n) (h : 0 < D.componentCount) :
  D.enhancedStateSum =
    (LaurentPolynomial.T 1 + LaurentPolynomial.T (-1)) *
      (LaurentPolynomial.eval₂ (Int.castRingHom (LaurentPolynomial ℤ))
          (-LaurentPolynomial.genericUnit ℤ))
        D.jonesPolynomial
Used by 1

TheoremTwo states differing exactly at a crossing do not both have two circles through it#

So along an edge of the cube of resolutions two circles merge into one, one circle splits into two, or one circle through the crossing is replaced by one circle.

TauCeti.PDCode.card_circlesAt_add_card_circlesAt_le_three {n : ℕ} (D : TauCeti.PDCode n)
  {s t : Fin n → Bool} {c : Fin n} (hst : ∀ (j : Fin n), j ≠ c → s j = t j) (hc : s c ≠ t c) :
  (D.circlesAt s c).card + (D.circlesAt t c).card ≤ 3
Used by 4

TheoremThe boundary-count criterion for noninterleaving#

A chord diagram on a nonempty boundary circle, with matching an involution σ and m = n - orbitCount σ bands, has exactly m + 1 boundary cycles if and only if no two of its bands interleave.

Function.Involutive.orbitCount_finRotate_mul_add_orbitCount_eq_iff {n : ℕ} [NeZero n]
  {σ : Equiv.Perm (Fin n)} (hinv : Function.Involutive ⇑σ) :
  TauCeti.orbitCount (finRotate n * σ) + TauCeti.orbitCount σ = n + 1 ↔ σ.IsNoncrossingMatching

TheoremTauCeti.Khovanov.isFrobenius#

The dual numbers with the Khovanov comultiplication satisfy the Frobenius equation.

TauCeti.Khovanov.isFrobenius.{u_1} (R : Type u_1) [CommSemiring R] :
  Coalgebra.IsFrobenius R (DualNumber R)

DefinitionCategoryTheory.Functor.cubeComplex#

The signed totalization of the commutative cube F: in degree r it is the biproduct of the vertices F(S) of height #S = r, with differential the sum of the edge maps F(S) ⟶ F(S ∪ {a}), signed by (-1) to the number of elements of S below a. It is characterised by the summand inclusions Functor.cubeComplexι and projections Functor.cubeComplexπ, and by Functor.ι_cubeComplex_d.

CategoryTheory.Functor.cubeComplex.{w, v, u} {C : Type u} [CategoryTheory.Category.{v, u} C]
  [CategoryTheory.Preadditive C] [CategoryTheory.Limits.HasFiniteBiproducts C] {ι : Type w}
  [Fintype ι] [LinearOrder ι] (F : CategoryTheory.Functor (Finset ι) C) : CochainComplex C ℤ
Used by 3

AbbreviationTauCeti.Khovanov.CircleTensor#

The circle tensor of a finite set ι of circles: the tensor product of one copy of the Khovanov Frobenius algebra R[ε] for each circle. It is a commutative R-algebra.

TauCeti.Khovanov.CircleTensor.{u, u_1} (R : Type u) [CommSemiring R] (ι : Type u_1) :
  Type (max u u_1)
Used by 5

DefinitionTauCeti.Khovanov.quantumGrading#

The quantum grading of the Khovanov Frobenius algebra R[ε]: the basis vector 1 spans degree 1, the basis vector ε spans degree -1, and every other degree is zero. It is the grading of the free module on the basis 1, ε by TauCeti.Khovanov.quantumDegree, transported to R[ε].

TauCeti.Khovanov.quantumGrading.{u} (R : Type u) [CommRing R] :
  TauCeti.InternalGrading R (DualNumber R) ℤ

DefinitionTauCeti.Khovanov.fiberwiseSplit#

The split map along f, adjoint to multiplication along its fibres. It maps the tensor on τ to the tensor on σ; a two-element fibre splits that circle.

TauCeti.Khovanov.fiberwiseSplit.{u_1, u_3, u_4} {R : Type u_1} [CommSemiring R] {σ : Type u_3}
  {τ : Type u_4} [Fintype σ] [Fintype τ] [DecidableEq τ] (f : σ → τ) :
  TauCeti.Khovanov.CircleTensor R τ →ₗ[R] TauCeti.Khovanov.CircleTensor R σ
Uses 1 · Used by 3

DefinitionTauCeti.PDCode.resolutionMergeMap#

Multiplication on the two circles merged at c, and identity on every other factor of the actual resolved-circle tensor. The one-circle target condition follows from the source count.

TauCeti.PDCode.resolutionMergeMap.{u} {n : ℕ} (D : TauCeti.PDCode n) {s t : Fin n → Bool}
  {c : Fin n} (hst : ∀ (j : Fin n), j ≠ c → s j = t j) (hc : s c ≠ t c)
  (hs : (D.circlesAt s c).card = 2) (R : Type u) [CommSemiring R] :
  TauCeti.Khovanov.CircleTensor R (D.ResolvedCircle s) →ₐ[R]
    TauCeti.Khovanov.CircleTensor R (D.ResolvedCircle t)
Uses 2 · Used by 2

DefinitionTauCeti.PDCode.resolutionSplitMap#

Comultiplication on the circle through c, splitting it into the two circles of the target through c, and identity on every other factor of the actual resolved-circle tensor. The one-circle source condition follows from the target count.

TauCeti.PDCode.resolutionSplitMap.{u} {n : ℕ} (D : TauCeti.PDCode n) {s t : Fin n → Bool}
  {c : Fin n} (hst : ∀ (j : Fin n), j ≠ c → s j = t j) (hc : s c ≠ t c)
  (ht : (D.circlesAt t c).card = 2) (R : Type u) [CommSemiring R] :
  TauCeti.Khovanov.CircleTensor R (D.ResolvedCircle s) →ₗ[R]
    TauCeti.Khovanov.CircleTensor R (D.ResolvedCircle t)
Uses 3 · Used by 2

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