injective function
41Open and closed maps — In topology, an open map is a function between two topological spaces which maps open sets to open sets.[1] That is, a function f : X → Y is open if for any open set U in X, the image f(U) is open in Y. Likewise, a closed map is a function… …
42Domain (mathematics) — In mathematics, the domain of a given functionis the set of input values for which the function is defined. [Paley, H. Abstract Algebra , Holt, Rinehart and Winston, 1966 (p. 16).] For instance, the domain of cosine would be all real numbers,… …
43Outline of discrete mathematics — The following outline is presented as an overview of and topical guide to discrete mathematics: Discrete mathematics – study of mathematical structures that are fundamentally discrete rather than continuous. In contrast to real numbers that have… …
44List of basic discrete mathematics topics — Discrete mathematics, also called finite mathematics, is the study of mathematical structures that are fundamentally , in the sense of not supporting or requiring the notion of continuity. Most, if not all, of the objects studied in finite… …
45Perfect space — In mathematics, in the field of topology, perfect spaces are spaces that have no isolated points. In such spaces, every point can be approximated arbitrarily well by other points given any point and any topological neighborhood of the point,… …
46Identifiability condition — In mathematics, the identifiability condition is defined as:f(x) = f(y) Leftrightarrow x = y quad forall x,ywhich says that if a function evaluates the same, then the arguments must be the same. I.e., a function is identifiable iff it is one to… …
47Bourbaki–Witt theorem — In mathematics, the Bourbaki–Witt theorem in order theory, named after Nicolas Bourbaki and Ernst Witt, is a basic fixed point theorem for partially ordered sets. It states that if X is a chain complete poset, and : f : X o X such that : f (x)… …
48Large countable ordinal — In the mathematical discipline of set theory, there are many ways of describing specific countable ordinals. The smallest ones can be usefully and non circularly expressed in terms of their Cantor normal forms. Beyond that, many ordinals of… …
49Factorization — This article is about the mathematical concept. For other uses, see Factor and Integer factorization. A visual illustration of the polynomial x2 + cx + d = (x + a)(x + b) where… …
50König's theorem (set theory) — For other uses, see König s theorem. In set theory, König s theorem (named after the Hungarian mathematician Gyula König) colloquially states that if the axiom of choice holds, I is a set, mi and ni are cardinal numbers for every i in I , and m i …
