A new construction of canonical extensions of lattices
30/08/2013 Sexta-feira, 30 de Agosto de 2013, 14h30m, IIIUL - Sala B1-01
Miroslav Haviar (M Bel University, Banská Bystrica, Slovakia)
Instituto para a Investigação Interdisciplinar da Universidade de Lisboa
Canonical extensions of algebras have their origin in famous 1951-52 papers of B. Jónsson and A. Tarski on Boolean algebras with operators. When the members of a variety of lattice-based algebras are algebraic models of a logic, canonicity (meaning that algebraic identities are preserved when constructing canonical extensions of algebras) leads to completeness for the associated logic. The concept has been intensively studied for distributive lattice expansions, and more generally to lattice and even poset expansions, in the last two decades (M. Gehrke, M.J. Gouveia, J. Harding, B. Jónsson, A. Palmigiano, H.A. Priestley, and others).
A new construction of the canonical extensions of bounded lattices will be presented which is in the spirit of the theory of natural dualities. At the level of objects, this can be achieved similarly as in the distributive case, where Priestley duality is used. In the non-distributive case, a dual topological representation of bounded lattices due to M. Plošcica (1995) will be exploited which is less-known than the classical one due to A. Urquhart (1978). At the level of morphisms, a duality due to Allwein a Hartonas (1993) will be recasted and applied. (A joint work with Andrew P.K. Craig and Hilary A. Priestley)