In my research I confront a variant of the vertex cover problem as follows:
Given a graph G, a vertex v and a number k, to decide whether G has a vertex cover of size k that contain v.
I have search all over literature and could not find a similar problem. I am interested in the complexity of this problem ( I have proved that it complete for $P^NP[long]$ ).
The question is have you ever seen such variant of vertex cover problem? How do you call this problem ?