  In a recent paper, Basu, Hildebrand, and Molinaro established that the set of
continuous minimal functions for the 1-dimensional Gomory-Johnson infinite
group relaxation possesses a dense subset of extreme functions. The
$n$-dimensional version of this result was left as an open question. In the
present paper, we settle this query in the affirmative: for any integer $n \geq
1$, every continuous minimal function can be arbitrarily well approximated by
an extreme function in the $n$-dimensional Gomory-Johnson model.
