Abstract
This paper has two aims: to aid a non-logician to construct uncountable examples by reducing the problems to finitary problems, and also to present some construction solving open problems. We assume the diamond forℵ 1 and solve problems in Boolean algebras, existentially closed groups and Banach spaces. In particular, we show that for a given countable e.c. groupM there is no uncountable group embeddable in everyG \(G L_{L,\omega } \)-equivalent toM; and that there is a non-separable Banach space with noℵ 1 elements, no one being the closure of the convex hull of the others. Both had been well-known questions. We also deal generally with inevitable models (§4).
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The author would like to thank the NSF for partially supporting this research by grants H144-H747 and MCS-76-08479, and the United States-Israel Binational Science Foundation for partially supporting this research.
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Shelah, S. Uncountable constructions for B.A. e.c. groups and banach spaces. Israel J. Math. 51, 273–297 (1985). https://doi.org/10.1007/BF02764721
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DOI: https://doi.org/10.1007/BF02764721