### Densities of ultraproducts of Boolean algebras

by Koppelberg and Shelah. [KpSh:415]

Canadian J Math Journal Canadien de Mathematiques, 1995

We answer three problems by J. D. Monk on cardinal invariants of
Boolean algebras. Two of these are whether taking the algebraic
density pi (A) resp. the topological density d(A) of a Boolean
algebra A commutes with formation of ultraproducts; the third one
compares the number of endomorphisms and of ideals of a Boolean
algebra.

Back to the list of publications