Bare canonicity of representable cylindric and polyadic algebras
Jannis Bulian, Ian Hodkinson · Annals of Pure and Applied Logic · 2013
We show that for finite n⩾3, every first-order axiomatisation of the varieties of representable n-dimensional cylindric algebras, diagonal-free cylindric algebras, polyadic algebras, and polyadic equality algebras contains an infinite number of non-canonical formulas. We also show that the class of structures for each of these varieties is non-elementary. The proofs employ algebras derived from random graphs.