Usage:
<monomial_curve a1 ... an i
Sets i = the defining ideal of the projective
curve given parametrically on an affine piece by
t ---> ( t^a1, ... ,t^an ).
The ideal is defined in the current ring, which
MUST HAVE AT LEAST n+1 variables of equal degree at
the beginning of its list of variables.
Parameters:
a1, ... ,an = nonnegative integers.
We must have n > 0.
Output values:
i = homogeneous ideal of the curve, defined over the
current ring.
The script forms the subring of the polynomial ring
in 2 variables t[1] and t[2] generated by
(t[1]^m, ... , t[1]^(m-ai) t[2]^ai , ... ),
where m is the maximum of the ai,
and calls pushforward1 to compute the relations on it.
Note that the result will be a degenerate curve if
any of the ai are repeated OR IF ONE OF THE ai=0.
Caveats:
The setdegs commands produce a spurious
"; warning: module isn't homogeneous" line, which
may be ignored.