TOOLS FOR YOUR FORCING CONSTRUCTION
TOOLS FOR YOUR FORCING CONSTRUCTION
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用于强制施工的工具
DOI：
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发表时间：
1992
期刊：
影响因子：
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通讯作者：
M. Goldstern
中科院分区：
文献类型：
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作者：
M. Goldstern
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A preservation theorem is a theorem of the form: "If hP�,Q� : � < �i is an iteration of forcing notions, and every Qsatisfies ' in V P� , then Psatisfies '." We give a simplified version of a general preservation theorem for countable support iteration due to Shelah. This version is particularly useful for problems dealing with sets of reals. We give several examples of applications, among them "countable support iteration of proper ! ! -bounding forcing notions is ! ! -bounding." We also review the basic facts about countable support iteration and proper forcing, as well as Souslin proper forcing notions.