Pregroup representable expansions of residuated lattices
Andrew Craig, Claudette Robinson
TL;DR
The paper advances the representability of algebraic structures beyond relation algebras by proving that distributive involutive FL-algebras ($DInFL$) and distributive quasi relation algebras ($DqRA$) can be realized as algebras of binary relations built from pregroups and their generalizations. Central to the approach are up-set constructions $ extsf{Up}(P, ext{≤})$ and $ extsf{Up}(P^2,owtie)$, together with the $oldsymbol{igtriangleup}$-map (a Cayley-like embedding) and its preservation properties under Conditions such as $W$; for pregroups these embeddings preserve the linear negations, yielding representability for $DInFL$, while ortho pregroups enable $DqRA$ representations via the extended $ eg$-operator. The work provides explicit finite representations from products of groups, illustrating the method and suggesting broader applicability to language-analytic and computational contexts. It also outlines future directions, including partially defined algebraic structures and potential non-representability results, which could further illuminate the boundary between representable and non-representable $DInFL$- and $DqRA$-type algebras.
Abstract
Group representable relation algebras play an important role in the study of representable relation algebras. The class of distributive involutive FL-algebras (DInFL-algebras) generalises relation algebras, as well as Sugihara monoids and MV-algebras. We construct DInFL-algebras from pregroups and show that they can be represented as algebras of binary relations. Even for finite pregroups we obtain relational representations of DInFL-algebras with non-Boolean lattice reducts. If the pregroup is enriched with a particular unary order-reversing operation, then our construction yields representation results for distributive quasi relation algebras.
