Non-solvable groups are not in FO+MOD+M - AJ2[REG]

Abstract

Motivated by the open question whether TC0 = NC1 we consider the case of linear size TC0. We use the connections between circuits, logic, and algebra, in particular the characterization of TC 0 in terms of finitely typed monoids. Applying algebraic methods we show that the word problem for finite non-solvable groups cannot be described by a FO+MOD+MAJ[REG] formula using only two variables. This implies a separation result of FO[REG]-uniform linear TC0 from linear NC1. © Springer-Verlag Berlin Heidelberg 2009.