Classification of congruences of twisted partition monoids

The twisted partition monoid P(n)(Phi )is an infinite monoid obtained from the classical finite partition monoid P-n by taking into account the number of floating components when multiplying partitions. The main result of this paper is a complete description of the congruences on P-n(Phi). The succinct encoding of a congruence, which we call a C-pair, consists of a sequence of n + 1 congruences on the additive monoid N of natural numbers and a certain (n + 1) x N matrix. We also give a description of the inclusion ordering of congruences in terms of a lexicographic-like ordering on C-pairs. This is then used to classify congruences on the finite d-twisted partition monoids P-n,d(Phi), which are obtained by factoring out from P-n(Phi) the ideal of all partitions with more than d floating components. Further applications of our results, elucidating the structure and properties of the congruence lattices of the (d-)twisted partition monoids, will be the subject of a future article. (C) 2021 Elsevier Inc. All rights reserved.