Abstract
Once we start measuring mathematical objects using infinite cardinals we are led naturally into two-cardinal combinatorics which is a field about combinatorial constructions with associated two cardinals. Various internal and external questions can be asked, all related to the relation between the two associated cardinals, e.g.:
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What could be heights of superatomic Boolean algebras with countable width?
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What are the possible sizes of Hausdorff spaces with points Gδ and countable Lindelof degree?
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Is it possible to construct a c.c.c forcing notion (and in particular a cardinal preserving forcing notion) that adds a function f: ω2 × ω2 → ω which isn’t constant on a product of any two infinite sets?
The exponential function. This is undoubtedly the most important function in mathematics.
Walter Rudin; Prologue to Real and Complex Analysis
The author was partially supported by the NSF Grant DMS-9505098. The author was also partially supported during the conference by Centre de Recerca Matemàtica (CRM) for which he is very grateful to the organizers of the conference: Joan Bagaria and Adrian Mathias.
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Koszmider, P. (1998). Applications of ρ-Functions. In: Di Prisco, C.A., Larson, J.A., Bagaria, J., Mathias, A.R.D. (eds) Set Theory. Springer, Dordrecht. https://doi.org/10.1007/978-94-015-8988-8_6
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DOI: https://doi.org/10.1007/978-94-015-8988-8_6
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