Singular chains of a mapping torus #
The fibre of the mapping torus of φ : F ≃ₜ F has a canonical inclusion at height zero.
Traversing the cylinder from height zero to height one gives a homotopy from this inclusion after
φ to the inclusion itself. This file transfers that homotopy to singular chains and homology,
and constructs the resulting map from the mapping cone of id - φ_* to the singular chains of
the mapping torus.
Thus the inclusion coequalizes the identity and monodromy maps, first up to chain homotopy and
then on homology. Equivalently, its composite with id - φ_* is null-homotopic. The universal
property of the mapping cone then gives the chain map which underlies the Wang sequence.
Main declarations #
TauCeti.MappingTorus.singularChainHomotopy: the composite of the monodromy chain map with the fibre-inclusion chain map is chain-homotopic to the fibre-inclusion map.TauCeti.MappingTorus.homologyMap_monodromy_comp_incl: the corresponding equality on singular homology.TauCeti.MappingTorus.wangEndomorphism: the chain endomorphismid - φ_*of the fibre.TauCeti.MappingTorus.homologyMap_monodromyChainMap_zero: on a path-connected fibre the monodromy induces the identity ofH₀(F).TauCeti.MappingTorus.wangMappingConeMap: the canonical map from the mapping cone ofid - φ_*to the singular chains of the mapping torus.TauCeti.MappingTorus.wangMappingConeMapOfSemiconj: the functorial map between these cones induced by a map intertwining two monodromies.
The construction follows the mapping-torus derivation of the Wang sequence; see A. Hatcher,
Algebraic Topology, Section 2.2. The chain homotopy itself is obtained from Mathlib's
homotopy invariance of singular chains, TopCat.Homotopy.singularChainComplexFunctorObjMap.
The endomorphism of singular chains induced by the monodromy of a mapping torus.
Instances For
The monodromy chain map is the singular-chain functor applied to the monodromy.
The map on singular chains induced by inclusion of the fibre at height zero.
Instances For
The fibre-inclusion chain map is the singular-chain functor applied to the fibre inclusion.
The singular-chain map induced by monodromy followed by fibre inclusion is chain-homotopic to the fibre-inclusion chain map.
Instances For
The components of the singular-chain homotopy are those induced by the cylinder homotopy.
On singular homology, the map induced by the fibre inclusion is unchanged after precomposition with the monodromy map.
The Wang endomorphism id - φ_* on the singular chains of the fibre.
Instances For
The Wang endomorphism is the identity minus the monodromy chain map.
On homology, the Wang endomorphism is the identity minus the map induced by monodromy.
On a path-connected fibre the monodromy induces the identity of H₀(F).
The fibre inclusion after id - φ_* is null-homotopic. The sign is chosen so that the
endomorphism on the fibre is literally id - φ_*, rather than its negative.
Instances For
The null-homotopy used in the Wang mapping-cone map is the negative of the canonical monodromy homotopy.
The chain-level mapping cone of id - φ_* used in the mapping-cone formulation of the
Wang sequence.
Instances For
The canonical chain map from the mapping cone of id - φ_* to singular chains of the
mapping torus. It is induced by fibre inclusion and the canonical monodromy homotopy.
Instances For
The Wang mapping-cone map restricts to fibre inclusion on the unsuspended summand.
The Wang mapping-cone map restricts to fibre inclusion on the unsuspended summand.
On the suspended fibre summand, the Wang mapping-cone map is the negative of the canonical monodromy homotopy.
On the suspended fibre summand, the Wang mapping-cone map is the negative of the canonical monodromy homotopy.
The map on singular chains induced by a map between the fibres of two mapping tori.
Instances For
The fibre chain map is the singular-chain functor applied to the map of fibres.
The map on singular chains induced by a map of mapping tori.
Instances For
The mapping-torus chain map is the singular-chain functor applied to the map of mapping tori.
A map intertwining two monodromies gives a commuting square on singular chains.
A map intertwining two monodromies gives a commuting square on singular chains.
Fibre inclusion is natural for maps of mapping tori.
Fibre inclusion is natural for maps of mapping tori.
The fibre chain map intertwines the Wang endomorphisms id - φ_* and id - ψ_*.
The fibre chain map intertwines the Wang endomorphisms id - φ_* and id - ψ_*.
The commuting square between the Wang endomorphisms associated to a map intertwining monodromies.
Instances For
The map between Wang mapping cones induced by a map intertwining the monodromies.
Instances For
On the unsuspended fibre summand, the induced map of Wang cones is the fibre chain map.
On the unsuspended fibre summand, the induced map of Wang cones is the fibre chain map.
On the suspended fibre summand, the induced map of Wang cones is again the fibre chain map.
On the suspended fibre summand, the induced map of Wang cones is again the fibre chain map.