'When combined with the HLT method this is known as HLT+Lookahead
method of coset enumeration, described on pg. 164 [1]. Whenever
``define`` aborts due to lack of space available this procedure is
executed. This routine helps in recovering space resulting from
"coincidence" of cosets.'

def look_ahead(self):

    R = self.fp_group.relators
    p = self.p
    for beta in self.omega:
        for w in R:
            self.scan(beta, w)
            if (p[beta] < beta):
                break
