1302.0349 (Terry A. Loring)

Quantitative K-theory and spin Chern numbers    [PDF]

Terry A. Loring

We validate a method of computing spin Chern numbers that was developed with Hastings and only conjectured to be correct. Specifically, the Pfaffian Bott index can be computed by the "log method" for commutator norms up to a specific constant. We establish lower bounds on the distance almost commuting unitaries must be moved to change an index. This is done for the Bott index, the winding number index for general unitary matrices, and for the Pfaffian Bott index for self-dual matrices.

View original: http://arxiv.org/abs/1302.0349