vertices count in a mesh

Hum, I don't know if you can just delete a vertex, since a surface is made up by triangles, and each triangle needs three vertices.

So if you (theoretically) delete only one vertex, how can the related triangle exist ?

I *think* that you should delete the triangle, so to delete the one vertex you need to be deleted, and then re-create the triangle with the remaining two vertices, plus one that should come from another adiacent triangle.

I'm just guessing...