Thom space

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Thom space

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Formed by by collapsing the complement of the normal bundle?

Thought of as a twisted suspension, since for a trivial bundle \(B\times{\mathbf{R}}^n \xrightarrow{p} B\) we have \(\mathop{\mathrm{Th}}(p) = {\Sigma}^n B_+\).

Coboridsm classes \(\Omega_*\) as stable homotopy groups of \({\operatorname{MO}}\):

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The Pontrayagin-Thom construction

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Thom spectra

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Can also construct \(\mathop{\mathrm{Th}}(p)\) by applying a fiberwise one-point compactification on \(E\) and identifying all the added points to a single basepoint.

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Relation to topological K theory: attachments/Pasted%20image%2020220325221544.png

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Orientations

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See complex oriented cohomology theory.

Can view as a twisted suspension spectrum?

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The Thom Diagonal

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Product formula

Relates to smash product: attachments/Pasted%20image%2020220403212454.png

Thom isomorphism theorem

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Relation to Euler class

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Cofiber sequence

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Examples

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#homotopy/bundles #todo/add-references