Cardinality
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In mathematics, cardinality is an inherent property of sets, roughly meaning the number of individual objects they contain, which may be infinite. The concept is understood through one-to-one correspo
Large cardinal hierarchy, ordered from bottom to top in terms of strength
Georg Cantor, c. 1870
Bernard Bolzano
Hausdorff 1913 1921
Skolem's paradox
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In mathematical logic and philosophy, Skolem's paradox is the apparent contradiction that a countable model of first-order set theory could contain an uncountable set. The paradox arises from part of
Cardinality
…and have often strange or unintuitive consequences. However, every theory of cardinality using standard logical foundations of mathematics admits Skolem's paradox. The basic concepts of cardinality go back as early as the 6th century BCE, and there are several close encounters with it throughout history, however…
Thoralf Skolem, after whom the paradox is named