8 citations · 26 across the 13 of their papers we have counts for
7 papers · 1 filter
A corrected strategy for proving no finite variable axiomatisation exists for RRA
Rob Egrot, Robin Hirsch
We show that if for all finite there is a pair of non-isomorphic finite digraphs satisfying some additional conditions, one of which is that they cannot be distinguished in a c…
First-order axiomatisations of representable relation algebras need formulas of unbounded quantifier depth
Rob Egrot, Robin Hirsch
Using a variation of the rainbow construction and various pebble and colouring games, we prove that RRA, the class of all representable relation algebras, cannot be axiomatised by…
Recursive axiomatisations from separation properties
Rob Egrot
We define a fragment of monadic infinitary second-order logic corresponding to an abstract separation property. We use this to define the concept of a separation subclass. We use m…
Recursive axiomatizations for representable posets
Rob Egrot
We use model theoretic techniques to construct explicit first-order axiomatizations for the classes of posets that can be represented as systems of sets, where the order relation i…
No finite axiomatizations for posets embeddable into distributive lattices
Rob Egrot
Let and be cardinals with . We show that the class of posets that can be embedded into a distributive lattice via a map preserving all existing meets and jo…
Non-elementary classes of representable posets
Rob Egrot
A poset is -representable if it can be embedded into a field of sets in such a way that all existing joins, and all existing \emph{finite} meets are preserved. We show that…
Representable posets
Rob Egrot
A poset is representable if it can be embedded in a field of sets in such a way that existing finite meets and joins become intersections and unions respectively (we say finite mee…