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If you have an infinite set X of cardinality k, then what is the cardinality of Sym(X) - the group of permutations of X ?
If you have an infinite set X of cardinality k, then what is the cardinality of Sym(X) - the group of permutations of X ?
The proof that I have in mind is as follows - $\text{Gal }(\overline{\mathbb Q}/\mathbb Q)$ is a proper uncountable subgroup of the group of permutations on countably many symbols, hence the latter is uncountable. . But it needs a lot of jargon from topology and algebra. Is there a neat proof ...