cohomology

# Contents

## Idea

The first of the Chern classes. The unique characteristic class of circle bundles / complex line bundles.

## Definition

### In bare homotopy-type theory

As a universal characteristic class, the first Chern class is the weak homotopy equivalence

${c}_{1}:BU\left(1\right)\stackrel{\simeq }{\to }K\left(ℤ,2\right)\phantom{\rule{thinmathspace}{0ex}}.$c_1 : B U(1) \stackrel{\simeq}{\to} K(\mathbb{Z},2) \,.
Revised on May 30, 2012 15:46:18 by Urs Schreiber (94.136.12.233)