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If c is a limit cardinal, how do you prove card(union E) < c when card(E) < c and card(e) < c for all e in E? [closed]

set-theory

may 6 11 at 6:36 Jason 1,944●1●5●16

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An exterior angle theorem for n-dimensional polytopes?

geometry polytopes

aug 25 10 at 3:45 Allen Knutson 12.4k●1●23●64

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What’s wrong with the surreals?

set-theory lo.logic soft-question big-picture

jul 1 10 at 11:04 Serge R. 66●3

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Nice proof of the Jordan curve theorem?

gt.geometric-topology at.algebraic-topology

may 11 at 19:35 Vladimir Kanovei 11●1