Index Set Complexity for Congruence Lattices of Lattices
摘要
We analyze computable algebras (in the sense of universal algebra) in terms of index set complexity, specifically as regards their congruence lattices. We characterize simplicity of lattices as complete at the level \(\varPi ^0_2\) , mirroring a result of Khoussainov and Morozov (2010) for groups. Finiteness of the congruence lattice is proved complete at the level \(\varSigma ^0_3\) ; and subdirect irreducibility at the level \(\varSigma ^0_3\) .