Given two multiplicity types
μ and μ′, the following two conditions are shown to be equivalent: (1) For every
algebra A of multiplicity type μ there exists an algebra A′ of multiplicity type μ′ such
that A and A′ have exactly the same congruence relations. (2) For every
k > 0,μk+ μk+1+⋯≦ μk′+ μk+1′ +⋯ .