A graph is said to be 1/2-transitive if its automorphism group acts transit
ively on vertices and edges but not on arcs. For each n greater than or equ
al to 11, a 1/2-transitive graph of valency 4 and girth 6, with the automor
phism group isomorphic to A(n) x Z(2), is given. (C) 1999 Academic Press.