3 papers
math.LO2019
Lindenbaum Method
Alex Citkin, Alexei Muravitsky
During his brief life, the Polish mathematician and logician Adolf Lindenbaum (1904--1941) contributed to mathematical logic, among other things, by several significant achievement…
math.LO2017
Projective Algebras and Primitive Subquasivarieties in Varieties with Factor Congruences
Alex Citkin
We prove that in the varieties where every compact congruence is a factor congruence and every nontrivial algebra contains a minimal subalgebra, a finitely presented algebra is pro…
cs.LO2012
Characteristic formulas over intermediate logics
Alex Citkin
We expand the notion of characteristic formula to infinite finitely presentable subdirectly irreducible algebras. We prove that there is a continuum of varieties of Heyting algebra…