Bug in GBNP?

[klauslux]

The following causes an error in GBNP (GAP 4.10.2):

LoadPackage("gbnp");
A:=FreeAssociativeAlgebraWithOne(Rationals,"a","b");
a:=A.1;
b:=A.2;
rels := [
  a^3, a^2*b, a*b^2+a^2, b*a^2, a^3+b^2+b*a, a*b^2+a*b*a, b*a*b+b*a^2, b^2*a+b*a^2,
  b^3+b*a^2, a^2*b*a, a*b*a^2, b*a^2*b
];
l:=List(rels,x->GP2NP(x));
Grobner(l);
Error, List Element: <list>[13] must have an assigned value in ...

[klauslux]

replacing rels[6] by rels[6] - rels[3] will avoid the bug. (rels[6] and rels[3] have the same
leading term)