The BNS invariants of the braid groups and pure braid groups of some surfaces
The BNS invariants of the braid groups and pure braid groups of some surfaces
We compute the Bieri-Neumann-Strebel invariants Σ1 for the full and pure braid groups of the sphere S2, the real projective plane RP2, the torus T and the Klein bottle K. For M=T or M=K, n≥2, we show that the action by homeomorphisms of Out(Pn(M)) on S(Pn(M)) contains certain permutations, under …