# Sh:415

- Koppelberg, S., & Shelah, S. (1995).
*Densities of ultraproducts of Boolean algebras*. Canad. J. Math.,**47**(1), 132–145. arXiv: math/9404226 DOI: 10.4153/CJM-1995-007-0 MR: 1319693 -
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. - Version 1994-04-12_10 (15p) published version (14p)

Bib entry

@article{Sh:415, author = {Koppelberg, Sabine and Shelah, Saharon}, title = {{Densities of ultraproducts of Boolean algebras}}, journal = {Canad. J. Math.}, fjournal = {Canadian Journal of Mathematics. Journal Canadien de Math\'ematiques}, volume = {47}, number = {1}, year = {1995}, pages = {132--145}, issn = {0008-414X}, mrnumber = {1319693}, mrclass = {03C20 (03E10 03G05 06E05)}, doi = {10.4153/CJM-1995-007-0}, note = {\href{https://arxiv.org/abs/math/9404226}{arXiv: math/9404226}}, arxiv_number = {math/9404226} }