... presentation of H by simple deletion of all occurrences of a set of generators of N. The effective nature of the processin this case will be exemplified in Section 7.3. A residually finite version of the ... completions of groups, Soviet Math. Dokl. 33 (1986), 822–825.[12]———, Grothendieck’s problem on profinite completions and representations of groups, K-Theory 4 (1990), 89–101.[13]L. Pyber, Groups of ... case of the general phenomenon thatif a class of groups G is closed under the formation of HNN extensions andamalgamated free products along finitely generated free groups, then one canembed groups...