A group presentation with a cyclic list of generators and relations has no nontrivial finite quotient of a group. In a finite image, all generator orders are odd. Choose the least prime dividing any nontrivial generator order and let be the predecessor of a generator whose order is divisible by . Conjugation by acts as squaring on , so the multiplicative order of modulo divides the order of . That multiplicative order is greater than one and divides , giving a prime divisor smaller than in the order of , a contradiction. This argument applies to any cycle length; it asserts absence of finite quotients, not infinitude of the presented group.
Past exam of the mathematics course of the University of Cambridge 2016 iii Paper 104 6 d i Solution Created 2026-10-03 Updated 2026-10-06
Every finitely presented group embeds in by . This direct product of groups is finitely presented: combine finite presentations of the factors and add the finitely many cross-commutation relations between their generators. Projection onto gives a nontrivial finite quotient of a group.