Paper detail

Maps of surface groups to finite groups with no simple loops in the kernel

Let $F_g$ denote the closed orientable surface of genus $g$. What is the least order finite group, $G_g$, for which there is a homomorphism $ψ$ from $π_1(F_g)$ to $G_g$ so that no nontrivial simple closed curve on $F_g$ represents an element in Ker($ψ$)? For the torus it is easily seen that $G_1 = Z_2 \times Z_2$ suffices. We prove here that $G_2$ is a group of order 32 and that an upper bound for the order of $G_g$ is given by $g^{2g +1}$. The previously known upper bound was greater than $2^{g{2^{2g}}}$.