Holmstrom D50 More about oriented theories

All the various notions of oriented theories. Example of oriented theories. Are there oriented theories which are not representable?

Most theories are oriented, but Witt groups are not! I have notes on an example which apparently proves this, by saying that any oriented theory will have connecting homomorphisms equal to zero in the setting of a closed subscheme with open complement (affine?????). Baptiste Calmes computes what happens for Witt groups.

Oriented theories

Oriented Borel-Moore homology, Oriented homology, Orientable cohomology, Oriented cohomology

Motivic cobordism, Algebraic cobordism

See Levine for more examples.

nLab page on D50 More about oriented theories

Created on June 9, 2014 at 21:16:15 by Andreas Holmström