arXiv math/94042261994-04-15math.LOmath.GN

Densities of ultraproducts of Boolean algebras

Sabine Koppelberg, Saharon Shelah

发表信息：: Canad. J. Math. 47 (1995), 132--145

英文摘要：

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.

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