50 research outputs found
Sigma theory for Bredon modules
We develop new invariants similar to the Bieri-Strebel-Neumann-Renz
invariants but in the category of Bredon modules (with respect to the class of
the finite subgroups of G). We prove that for virtually soluble groups of type
FP_{\infty} and finite extension of the Thompson group F the new invariants
coincide with the classical ones
Subgroup posets, Bredon cohomology and equivariant Euler characteristics
For a discrete group satisfying some finiteness conditions we give a
Bredon projective resolution of the trivial module in terms of projective
covers of the chain complex associated to certain posets of subgroups. We use
this to give new results on dimensions of and to reprove that for
virtually solvable groups, \underline{\cd}\Gamma=\vcd\Gamma. We also deduce a
formula to compute the Euler class of for virtually solvable
of type \FP_\infty and use it to compute orbifold Euler characteristics.Comment: 19 page