Enumeration of Latin squares with conjugate symmetry

Brendan D. McKay, Ian M. Wanless

Research output: Contribution to journalArticleResearchpeer-review

2 Citations (Scopus)

Abstract

A Latin square has six conjugate Latin squares obtained by uniformly permuting its (row, column, symbol) triples. We say that a Latin square has conjugate symmetry if at least two of its six conjugates are equal. We enumerate Latin squares with conjugate symmetry and classify them according to several common notions of equivalence. We also do similar enumerations under additional hypotheses, such as assuming the Latin square is reduced, diagonal, idempotent or unipotent. Our data corrected an error in earlier literature and suggested several patterns that we then found proofs for, including (1) the number of isomorphism classes of semisymmetric idempotent Latin squares of order (Formula presented.) equals the number of isomorphism classes of semisymmetric unipotent Latin squares of order (Formula presented.), and (2) suppose (Formula presented.) and (Formula presented.) are totally symmetric Latin squares of order (Formula presented.). If (Formula presented.) and (Formula presented.) are paratopic then (Formula presented.) and (Formula presented.) are isomorphic.

Original languageEnglish
Pages (from-to)105-130
Number of pages26
JournalJournal of Combinatorial Designs
Volume30
Issue number2
DOIs
Publication statusPublished - Feb 2022

Keywords

  • idempotent
  • Latin square
  • semisymmetric
  • symmetric
  • totally symmetric
  • unipotent

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