Semimorasses and Nonreflection at Singular Cardinals
Semimorasses and Nonreflection at Singular Cardinals
复制标题
奇异基数的半沼泽和不思考
DOI:
10.1016/0168-0072(93)e0068-y
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发表时间:
1995
期刊:
影响因子:
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通讯作者:
P. Koszmider
中科院分区:
文献类型:
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作者:
P. Koszmider
Some subfamilies of Pκ(λ), for κ regular, κ ⩽ λ, called (κ, λ)-semimorasses are investigated. For λ = κ+, they constitute weak versions of Velleman's simplified (κ, 1)-morasses, and for λ > κ+, they provide a combinatorial framework which in some cases has similar applications to the application of (κ, 1)-morasses with this difference that the obtained objects are of size λ ⩾ κ+, and not only of size κ+as in the case of morasses. New consistency results involve (compatible with CH) existence of nonreflecting objects of singular sizes of uncountable cofinality such as a nonreflecting stationary set in Pκ(λ), a nonreflecting nonmetrizable space of size λ, a nonreflecting nonspecial tree of size λ. We also characterize possible minimal sizes of nonspecial trees without uncountable branches.
DOI:
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