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  2. Bijection - Wikipedia

    en.wikipedia.org/wiki/Bijection

    A bijection, bijective function, or one-to-one correspondence between two mathematical sets is a function such that each element of the second set (the codomain) is the image of exactly one element of the first set (the domain).

  3. Bijection, injection and surjection - Wikipedia

    en.wikipedia.org/wiki/Bijection,_injection_and...

    In mathematics, injections, surjections, and bijections are classes of functions distinguished by the manner in which arguments (input expressions from the domain) and images (output expressions from the codomain) are related or mapped to each other.

  4. Involution (mathematics) - Wikipedia

    en.wikipedia.org/wiki/Involution_(mathematics)

    Any involution is a bijection.. The identity map is a trivial example of an involution. Examples of nontrivial involutions include negation (x ↦ −x), reciprocation (x ↦ 1/x), and complex conjugation (z ↦ z) in arithmetic; reflection, half-turn rotation, and circle inversion in geometry; complementation in set theory; and reciprocal ciphers such as the ROT13 transformation and the ...

  5. Equivalence relation - Wikipedia

    en.wikipedia.org/wiki/Equivalence_relation

    Any equivalence relation is the negation of an apartness relation, though the converse statement only holds in classical mathematics (as opposed to constructive mathematics), since it is equivalent to the law of excluded middle. Each relation that is both reflexive and left (or right) Euclidean is also an equivalence relation.

  6. Cantor's diagonal argument - Wikipedia

    en.wikipedia.org/wiki/Cantor's_diagonal_argument

    Define the bijection g(t) from T to (0, 1): If t is the n th string in sequence s, let g(t) be the n th number in sequence r ; otherwise, g(t) = 0.t 2. To construct a bijection from T to R, start with the tangent function tan(x), which is a bijection from (−π/2, π/2) to R (see the figure shown on the right).

  7. Homeomorphism - Wikipedia

    en.wikipedia.org/wiki/Homeomorphism

    In mathematics and more specifically in topology, a homeomorphism (from Greek roots meaning "similar shape", named by Henri Poincaré), [2] [3] also called topological isomorphism, or bicontinuous function, is a bijective and continuous function between topological spaces that has a continuous inverse function.

  8. Image (mathematics) - Wikipedia

    en.wikipedia.org/wiki/Image_(mathematics)

    Bijection, injection and surjection – Properties of mathematical functions Fiber (mathematics) – Set of all points in a function's domain that all map to some single given point Image (category theory) – term in category theory Pages displaying wikidata descriptions as a fallback

  9. Group (mathematics) - Wikipedia

    en.wikipedia.org/wiki/Group_(mathematics)

    The definition of a group does not require that = for all elements and in ⁠ ⁠. If this additional condition holds, then the operation is said to be commutative, and the group is called an abelian group. It is a common convention that for an abelian group either additive or multiplicative notation may be used, but for a nonabelian group only ...