Implication semilattice of 990 quasigroup equational laws
Abstract
In his quest to disprove a claim by Peirce that all lattices are distributive, Ernst Schr\"oder considered 135 years ago a list of 990 equational laws on quasigroups, analogous to associativity, such as (x // y) * z = (y // x) z. A quasigroup is a non-associative analogue of groups, specifically a set equipped with multiplication and right/left conjugate-division operations that are compatible. Each equation of interest identifies two three-variable expressions built from these operations. I determine all 114 equivalence classes of their conjunctions, and all implications between them. This includes as a small corner the five-element non-distributive lattice identified by Schr\"oder.
Turn this paper into a full lesson
ArcXiv compiles a staged curriculum from this paper: 8-12 lessons across beginner → advanced, synthesised section guides, visuals, flashcards, a quiz, exercises, and on-demand deep dives per section. Grounded in the abstract, never invented.