3 citations · 6 across the 4 of their papers we have counts for
5 papers
Quasi-positivity and recognition of products of conjugacy classes in free groups
Robert W. Bell, Rita Gitik
Given a group and a subset , an element is called quasi-positive if it is equal to a product of conjugates of elements in the semigroup generated by .…
On the cop number of generalized Petersen graphs
Taylor Ball, Robert W. Bell, Jonathan Guzman +2
We show that the cop number of every generalized Petersen graph is at most 4. The strategy is to play a modified game of cops and robbers on an infinite cyclic covering space where…
Combinatorial Methods for Detecting Surface Subgroups in Right-Angled Artin Groups
Robert W. Bell
We give a short proof of the following theorem of Sang-hyun Kim: if is a right-angled Artin group with defining graph , then contains a hyperbolic surface subgroup…
Injections of Artin groups
Robert W. Bell, Dan Margalit
We study those Artin groups which, modulo their centers, are finite index subgroups of the mapping class group of a sphere with at least 5 punctures. In particular, we show that an…
Braid groups are almost co-Hopfian
Robert W. Bell, Dan Margalit
Let B_n be the braid group on n > 3 strands. We prove that B_n modulo its center is co-Hopfian. We then show that any injective endomorphism of B_n is geometric in the sense that i…