dinates as follows.  Each point P of Y
| has an open neighborhood U in X with local coordinates (x_1, ..., x_n)
| such that the points of Y in U are precisely those whose last n - m
| coordinates are 0, that is, those points having coordinates of type
|
| (x_1, ..., x_m, 0, ..., 0).
|
| Let f : Z -&gt; X be a morphism, and let z be in Z.  We shall say that f is
| an &quot;immersion&quot; at z if there exists an open neighborhood Z_1 of z in Z
| such that the restriction of f to Z_1 induces an isomorphism of