Minimal dimension faithful linear representations of common finitely   presented groups
  For various finitely presented groups, including right angled Artin groups and free by cyclic groups, we investigate what is the smallest dimension of a faithful linear representation. This is done both over C and over fields of positive characteristic. In particular we show that Gersten's free by cyclic group has no faithful linear representation of dimension 4 or less over C, but has no faithful linear representation of any dimension over fields of positive characteristic. 
J.O.Button
math.GR