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TauCeti.AlgebraicTopology.Singular.Shuffle

The shuffle map on singular chains #

For topological spaces X and Y, TopCat.shuffle X Y R S is the Eilenberg--Mac Lane shuffle map from the tensor product of the singular chains of X and Y to the singular chains of X × Y. It is the simplicial shuffle map followed by the chain map induced by the canonical isomorphism Sing X × Sing Y ≅ Sing (X × Y). The construction is natural in both spaces and both coefficient objects.

The comparison with the simplicial shuffle map is recorded in both directions. In particular, composing with the map induced by the two projections recovers the simplicial shuffle map. This places the singular shuffle and Alexander--Whitney maps in the same product comparison and is the input for their Eilenberg--Zilber chain homotopies.

Main definitions and results #

References #

The Eilenberg--Mac Lane shuffle map C(X; R) ⊗ C(Y; S) ⟶ C(X × Y; R ⊗ S) on singular chains: the simplicial shuffle map, followed by the map induced by the monoidal comparison Sing X × Sing Y ⟶ Sing (X × Y).

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    @[simp]

    The singular shuffle map on the summand of a p-simplex x of X and a q-simplex y of Y is the image of the shuffle chain under the map to Sing (X × Y) classified by (x, y).

    @[simp]
    theorem TopCat.ιChainComplex_tensorHom_ιChainComplex_shuffle_f_assoc {C : Type u} [CategoryTheory.Category.{v, u} C] [CategoryTheory.Preadditive C] [CategoryTheory.MonoidalCategory C] [CategoryTheory.MonoidalPreadditive C] [CategoryTheory.Limits.HasCoproducts C] [∀ (T : C) (J : Type w), CategoryTheory.Limits.PreservesColimitsOfShape (CategoryTheory.Discrete J) (CategoryTheory.MonoidalCategory.tensorLeft T)] [∀ (T : C) (J : Type w), CategoryTheory.Limits.PreservesColimitsOfShape (CategoryTheory.Discrete J) (CategoryTheory.MonoidalCategory.tensorRight T)] {X Y : TopCat} (R S : C) {p q n : ℕ} (x : (toSSet.obj X).obj (Opposite.op { len := p })) (y : (toSSet.obj Y).obj (Opposite.op { len := q })) (h : p + q = n) {Z : C} (h✝ : ((toSSet.obj (CategoryTheory.MonoidalCategoryStruct.tensorObj X Y)).chainComplex (CategoryTheory.MonoidalCategoryStruct.tensorObj R S)).X n ⟶ Z) :

    The singular shuffle map on the summand of a p-simplex x of X and a q-simplex y of Y is the image of the shuffle chain under the map to Sing (X × Y) classified by (x, y).

    The singular composite alexanderWhitney ≫ shuffle is the simplicial composite conjugated by the canonical product comparison Sing (X × Y) ≅ Sing X × Sing Y.