COMPLETE QUOTIENT BOOLEAN-ALGEBRAS

被引:1
作者
KANAMORI, A [1 ]
SHELAH, S [1 ]
机构
[1] HEBREW UNIV JERUSALEM,DEPT MATH,JERUSALEM,ISRAEL
关键词
D O I
10.2307/2154916
中图分类号
O1 [数学];
学科分类号
0701 ; 070101 ;
摘要
For I a proper, countably complete ideal on the power set P(X) for some set X, can the quotient Boolean algebra P(X)/I be complete? We first show that, if the cardinality of X is at least omega(3),then having completeness implies;the existence of an inner model with a measurable cardinal. A well-known situation that entails completeness is when the ideal I is a (nontrivial) ideal over a cardinal kappa which is kappa(+)-saturated. The second author had established the sharp;result that it is consistent by forcing to have such an ideal over kappa = omega(1) relative to the existence of a Woodin cardinal. Augmenting his proof by interlacing forcings that adjoin Boolean suprema, we establish, relative to the same large cardinal hypothesis, the consistency of: 2(omega 1) = omega(3) and there is an ideal ideal I over omega(1) such that P(omega(1))/I is complete. (The cardinality assertion implies that there is no ideal over omega(1) which is omega(2)-saturated, and so completeness of the Boolean algebra and saturation of the ideal has been separated.)
引用
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页码:1963 / 1979
页数:17
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