surjection

英語（米国） (en-US) 英語（イギリス） (en-GB)

IPA（発音記号）

/sɜː(ɹ).d͡ʒɛk.ʃən/

名詞

(set theory) A function for which every element of the codomain is mapped to by some element of the domain; (formally) Any function f:X→Y for which for every y∈Y, there is at least one x∈X such that f(x)=y.

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To prove that f: A → B is a surjection, we must show that for every element b in B there exists an a in A with f(a) = b.

詳細

意味（1）

(set theory) A function for which every element of the codomain is mapped to by some element of the domain; (formally) Any function f:X→Y for which for every y∈Y, there is at least one x∈X such that f(x)=y.

In some special cases, however, the number of surjections A→B can be identified.

詳細

surjections （ 複数形 ）