Singular Manual: lpIsPrime

| ##### 7.7.9.0. lpIsPrime Procedure from library `fpaprops.lib` (see fpaprops_lib). Usage: lpIsPrime(G); G an ideal in a Letterplace ring Return: boolean Purpose: Check whether A/<LM(G)> is prime, that is when p1 * (A/<LM(G)>) * p2 != 0 for all p1, p2 in (A/<LM(G)> - {0}). Assume: - basering is a Letterplace ring - G is a Groebner basis Theory: lpIsPrime works with the monomial algebra A/<LM(G)>. A positive answer holds for both A/<LM(G)> and A/<G>, while a negative answer applies only to A/<LM(G)> and not necessarily to A/<G>. Example:
    LIB "fpaprops.lib";
    ring r = 0,(x,y),dp;
    def R = makeLetterplaceRing(5);
    setring R;
    ideal G = x(1)*x(2), y(1)*y(2); // K<x,y>/<xx,yy> is prime
    lpIsPrime(G);
    ==> 1

User manual for Singular version 4-1-1p3, 2018, generated by texi2html.