Talk:Semi-symmetric graph

The second sentence of the article
"... a graph is semi-symmetric if ... there is some pair of vertices that cannot be mapped into each other by a symmetry."

I wonder if this is correct. Isn't it enough that "there is some pair of vertices such that no symmetry maps the first into the second."? Maybe there's a proof that if there's a symmetry that maps vertexA to vertexB, there's an involution that does it. But the definition itself, the first sentence of the article, uses "vertex-transitive" which does not imply that the operation is an involution. Maproom (talk) 12:30, 17 August 2015 (UTC)
 * Yes, that looks like a mistake. I've switched it to your wording. —David Eppstein (talk) 17:50, 17 August 2015 (UTC)