injective
含义: Describing a function in which every element of the codomain is mapped to by at most one element of the domain, ensuring that distinct inputs always produce distinct outputs. Also called one-to-one.
An injective function never maps two different inputs to the same output, though some elements of the codomain may have no preimage at all. Injectivity is one of the three key properties of functions (alongside surjectivity and bijectivity) studied in set theory and abstract algebra. In database design, an injective mapping ensures uniqueness constraints. The concept is fundamental to proofs about cardinality and to understanding invertibility of functions.
例句
- The function f(x) = 2x is injective because no two distinct values of x produce the same output. 函数f(x) = 2x是单射的,因为没有两个不同的x值会产生相同的输出。La función f(x) = 2x es inyectiva porque no hay dos valores distintos de x que produzcan la misma salida.関数f(x) = 2xは単射である。なぜなら、異なるxの値が同じ出力を生成することはないからである。함수 f(x) = 2x는 단사이다. 서로 다른 x의 값이 같은 출력을 생성하는 일이 없기 때문이다.
- The lecturer demonstrated that the mapping was injective by showing that f(a) = f(b) necessarily implies a = b. 讲师通过证明f(a) = f(b)必然意味着a = b来说明该映射是单射的。El profesor demostró que la correspondencia era inyectiva mostrando que f(a) = f(b) implica necesariamente que a = b.講師はf(a) = f(b)ならば必ずa = bとなることを示して、その写像が単射であることを証明した。강사는 f(a) = f(b)이면 반드시 a = b임을 보여줌으로써 해당 사상이 단사임을 증명했다.
- An injective hash function guarantees that different inputs will never produce the same hash value, eliminating collisions entirely. 单射哈希函数保证不同的输入永远不会产生相同的哈希值,从而完全消除碰撞。Una función hash inyectiva garantiza que entradas diferentes nunca producirán el mismo valor hash, eliminando las colisiones por completo.単射ハッシュ関数は、異なる入力が同じハッシュ値を生成しないことを保証し、衝突を完全に排除する。단사 해시 함수는 서로 다른 입력이 같은 해시 값을 생성하지 않음을 보장하여 충돌을 완전히 제거한다.
发音
用法指南
语境: scientific, academic
语气: neutral
起源与历史
From Latin injectus (thrown in), past participle of inicere (to throw in), combining in- (into) and jacere (to throw). The mathematical term was introduced by the Bourbaki group in the mid-20th century.
文化背景
Era: Modern
Generation: All ages
Social background: Universal
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