# Sh:415

• Koppelberg, S., & Shelah, S. (1995). Densities of ultraproducts of Boolean algebras. Canad. J. Math., 47(1), 132–145.
• Abstract:
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.
• published version (14p)
Bib entry
@article{Sh:415,
author = {Koppelberg, Sabine and Shelah, Saharon},
title = {{Densities of ultraproducts of Boolean algebras}},
}