This procedure attempts to find a set of relations among the given subgroup's generators sufficient to define the subgroup. The result is returned as a grelgroup.

The algorithm uses Todd-Coxeter coset enumeration, which is an inherently non-terminating process for infinite groups. Therefore, the algorithm will halt with an exception if too many cosets are generated during an attempt to enumerate cosets of a subgroup. The point at which the coset enumeration terminates is controlled by the environment variable _EnvMaxCosetsToddCoxeter, which has the default value .

Error, (in group:-pres) too many cosets - subgroup may have infinite index; you can increase the coset limit by setting the environment variable _EnvMaxCosetsToddCoxeter to a value larger than 128000