Description: The Cantor Normal Form theorem. The function ( A CNF B ) , which maps a finitely supported function from B to A to the sum ( ( A ^o f ( a 1 ) ) o. a 1 ) +o ( ( A ^o f ( a 2 ) ) o. a 2 ) +o ... over all indices a < B such that f ( a ) is nonzero, is an order isomorphism from the ordering T of finitely supported functions to the set ( A ^o B ) under the natural order. Setting A = _om and letting B be arbitrarily large, the surjectivity of this function implies that every ordinal has a Cantor normal form (and injectivity, together with coherence cantnfres , implies that such a representation is unique). (Contributed by Mario Carneiro, 28-May-2015)
Ref | Expression | ||
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Hypotheses | cantnfs.s | |
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cantnfs.a | |
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cantnfs.b | |
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oemapval.t | |
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Assertion | cantnf | |