nLab twisted Umkehr map



Integration theory



Special and general types

Special notions


Extra structure





For EE a cohomology theory, and f:XYf \colon X \to Y a map of suitable spaces, an ordinary Umkehr map for the induced map E (f):E (Y)E (X)E^\bullet(f) \colon E^\bullet(Y) \to E^{\bullet}(X) is a dual morphism together with self-duality equivalences for E (X)E^\bullet(X) and E (Y)E^\bullet(Y) (orientation/Atiyah duality+Thom isomorphism).

More generally, E (X)E^\bullet(X) may not be self-dual, but its dual object may be twisted cohomology E +χ(X)E^{\bullet+ \chi}(X) for some twist χ\chi. In this case the Umkehr map goes not between the original spaces and their cohomology, but between twisted cohomology variants of these.


Abstract duality and Atiyah-Milnor-Spanier duality + Pontryagin-Thom collapse



D() Σ + L wheTop𝕊Mod D \coloneqq (-)^\vee\circ \Sigma^\infty_+ \coloneqq L_{whe} Top \to \mathbb{S}Mod

for the Spanier-Whitehead duality map which sends a topological space first to its suspension spectrum and then that to its dual object in the (∞,1)-category of spectra.

(ABG 11, def 10.3).


For XX a compact manifold, let X nX \to \mathbb{R}^n be an embedding and write S nX ν nS^n \to X^{\nu_n} for the classical Pontryagin-Thom collapse map for this situation, and write

𝕊X TX \mathbb{S} \to X^{-T X}

for the corresponding looping map from the sphere spectrum to the Thom spectrum of the negative tangent bundle of XX. Then Atiyah duality produces an equivalence

X TXDX X^{- T X} \simeq D X

which identifies the Thom spectrum with the dual object of Σ + X\Sigma^\infty_+ X in 𝕊Mod\mathbb{S} Mod and this constitutes a commuting diagram

X TX 𝕊 D(X*) DX \array{ && X^{- T X} \\ & \nearrow & \downarrow^{\mathrlap{\simeq}} \\ \mathbb{S} &\underset{D(X \to \ast)}{\to}& D X }

identifying the classical Pontryagin-Thom collapse map with the abstract dual morphism construction of prop. .

More generally, for WXW \hookrightarrow X an embedding of manifolds, then Atiyah duality identifies the Pontryagin-Thom collapse maps

𝕊X TXW TW \mathbb{S} \to X^{-T X} \to W^{- T W}

with the abstract dual morphisms

𝕊DXDW. \mathbb{S} \to D X \to D W \,.

(ABG 11, prop. 10.5).

Umkehr map


Given now ECRing E \in CRing_\infty an E-∞ ring, then the dual morphism 𝕊DX\mathbb{S} \to D X induces under smash product a similar Pontryagin-Thom collapse map, but now not in sphere spectrum-(∞,1)-modules but in EE-(∞,1)-modules.

EDX 𝕊E. E \to D X \otimes_{\mathbb{S}} E \,.

The image of this under the EE-cohomology functor produces

[DX 𝕊E,E]E. [D X \otimes_{\mathbb{S}} E, E] \to E \,.

If now one has a Thom isomorphism (EE-orientation) [DX 𝕊E,E][X,E] [D X \otimes_{\mathbb{S}} E, E] \simeq [X,E] that identifies the cohomology of the dual object with the original cohomology, then together with the above this produces the Umkehr map

[X,E][DX 𝕊E,E]E [X,E] \simeq [D X \otimes_{\mathbb{S}} E, E] \to E

that pushes the EE-cohomology of XX to the EE-cohomology of the point. Analogously if instead of the terminal map X*X \to \ast we start with a more general map XYX \to Y.

More generally a Thom isomorphism may not exists, but [DX 𝕊E,E][D X \otimes_{\mathbb{S}} E, E] may still be equivalent to a twisted cohomology-variant [X,E] χ[X,E]_{\chi} of [X,E][X,E], namely to [Γ X(χ),E][\Gamma_X(\chi),E], where χ:Π(X)ELineEMod\chi \colon \Pi(X) \to E Line \hookrightarrow E Mod is an (flat) EE-(∞,1)-module bundle on XX and and Γlim\Gamma \simeq \underset{\to}{\lim} is the (∞,1)-colimit (the generalized Thom spectrum construction). In this case the above yields a twisted Umkehr map.

(ABG 10, 9.1)


The following terms all refer to essentially the same concept:


Twisted Umkehr maps in topological K-theory are discussed (somewhat implicitly sometimes) in the literature on KK-theory. See the references at Poincaré duality algebra.

The general abstract formulation in stable homotopy theory is sketched in section 9 of

and in section 10 of

A review and applications to quantization of local prequantum field theory is in

Formalization in dependent linear type theory is discussed

Last revised on March 15, 2021 at 10:08:13. See the history of this page for a list of all contributions to it.