def __init__(self,ringstr="",ring=None):
'''Solvable polynomial ring constructor.
'''
if ring == None:
sr = StringReader( ringstr );
tok = GenPolynomialTokenizer(sr);
self.pset = tok.nextSolvablePolynomialSet();
self.ring = self.pset.ring;
else:
self.ring = ring;
if not self.ring.isAssociative():
print "warning: ring is not associative";
