“…This invariant is bounded from below by the virtual cohomological dimension vcd(G) of G, which is the cohomological dimension of any finite index torsion-free subgroup of G, and in many interesting cases these two quantities are in fact equal (e.g. see [15,9,1,19,27,2]). On the other hand, there are by now a number of examples showing that gd(G) can be strictly larger than vcd(G) (see [17,22,10,16]).…”