D.15.8.5 isAface

Usage:

isAface(a,gam0); a: ideal, gam0:intvec

Purpose:

Checks whether the face of the positive orthant,
that is spanned by all i-th unit vectors,
where i ranges amongst the entries of gam0,
is an a-face.

Return:

int

LIB "gitfan.lib";
ring R = 0,(T(1..4)),dp;
ideal I = T(1)*T(2)-T(4);
intvec w = 1,4;
intvec v = 1,2,4;
isAface(I,w); // should be 0
==> 0
"-----------";
==> -----------
isAface(I,v); // should be 1
==> 1