  In this work we consider triangulations of point sets in the Euclidean plane,
i.e., maximal straight-line crossing-free graphs on a finite set of points.
Given a triangulation of a point set, an edge flip is the operation of removing
one edge and adding another one, such that the resulting graph is again a
triangulation. Flips are a major way of locally transforming triangular meshes.
We show that, given a point set $S$ in the Euclidean plane and two
triangulations $T_1$ and $T_2$ of $S$, it is an APX-hard problem to minimize
the number of edge flips to transform $T_1$ to $T_2$.
