Logo
Unionpedia
Communication
Get it on Google Play
New! Download Unionpedia on your Android™ device!
Free
Faster access than browser!
 

General topology

Index General topology

In mathematics, general topology is the branch of topology that deals with the basic set-theoretic definitions and constructions used in topology. [1]

175 relations: Algebra over a field, Algebraic geometry, Algebraic topology, Algebraic variety, ArXiv, Associative algebra, Axiom of countable choice, Baire category theorem, Baire space, Ball (mathematics), Base (topology), Bijection, Boundary (topology), Box topology, Category (mathematics), Category of topological spaces, Characterizations of the category of topological spaces, Clopen set, Closed set, Closure (topology), Closure operator, Cocountable topology, Codomain, Cofiniteness, Compact space, Comparison of topologies, Complement (set theory), Complete metric space, Complex number, Connected space, Connectedness, Continuous function, Countable set, Counterexamples in Topology, Cover (topology), Cylinder set, David van Dantzig, David Van Nostrand, Dense set, Differential topology, Directed set, Discrete space, Disjoint sets, Domain of a function, Dover Publications, Duality (mathematics), Empty set, Equivalence class, Equivalence relation, Euclidean space, ..., Family of sets, Final topology, Finite set, Finite topological space, First-countable space, Fréchet space, Function (mathematics), Functional analysis, Geometric topology, George F. Simmons, Glossary of topology, Graph theory, Hausdorff space, Heine–Borel theorem, History of the separation axioms, Homeomorphism, Identity function, Identity of indiscernibles, If and only if, Image (mathematics), Index set, Indexed family, Initial topology, Interior (topology), Internet Archive, Intersection (set theory), Interval (mathematics), Inverse function, James Munkres, John L. Kelley, John von Neumann, Kolmogorov space, Kuratowski closure axioms, Limit of a sequence, Limit point, Lindelöf space, Linear map, List of examples in general topology, List of general topology topics, Local field, Locally compact space, Locally connected space, Long line (topology), Lower limit topology, Manifold, Mathematical object, Mathematics, Maurice René Fréchet, Maximal and minimal elements, Mereotopology, Metric (mathematics), Metric space, Metrization theorem, Natural topology, Necessity and sufficiency, Neighbourhood (mathematics), Neighbourhood system, Net (mathematics), Nicolas Bourbaki, Normal space, Normed vector space, Nowhere dense set, Open and closed maps, Open set, Order topology, Ordered pair, Ordinal number, Paracompact space, Partially ordered set, Partition of a set, Path (topology), Path graph, Point (geometry), Polynomial, Product topology, Projection (mathematics), Projection (set theory), Property, Quotient space (topology), Rational number, Real line, Real number, Regular space, Ryszard Engelking, Second-countable space, Separable space, Separated sets, Sequence, Sequential space, Set theory, Sierpiński space, Simplex, Simplicial complex, Solution set, Spectrum of a ring, Springer Science+Business Media, Stephen Willard, Subbase, Subset, Subspace topology, Surjective function, T1 space, Theorem, Theory of computation, Thesis, Tietze extension theorem, Topological indistinguishability, Topological ring, Topological space, Topological vector space, Topologist's sine curve, Topology, Totally disconnected space, Triangle inequality, Trivial topology, Tychonoff space, Tychonoff's theorem, Union (set theory), Unit interval, Urysohn and completely Hausdorff spaces, Urysohn's lemma, Vector space, Vertex (graph theory), Zariski topology, (ε, δ)-definition of limit. Expand index (125 more) »

Algebra over a field

In mathematics, an algebra over a field (often simply called an algebra) is a vector space equipped with a bilinear product.

New!!: General topology and Algebra over a field · See more »

Algebraic geometry

Algebraic geometry is a branch of mathematics, classically studying zeros of multivariate polynomials.

New!!: General topology and Algebraic geometry · See more »

Algebraic topology

Algebraic topology is a branch of mathematics that uses tools from abstract algebra to study topological spaces.

New!!: General topology and Algebraic topology · See more »

Algebraic variety

Algebraic varieties are the central objects of study in algebraic geometry.

New!!: General topology and Algebraic variety · See more »

ArXiv

arXiv (pronounced "archive") is a repository of electronic preprints (known as e-prints) approved for publication after moderation, that consists of scientific papers in the fields of mathematics, physics, astronomy, computer science, quantitative biology, statistics, and quantitative finance, which can be accessed online.

New!!: General topology and ArXiv · See more »

Associative algebra

In mathematics, an associative algebra is an algebraic structure with compatible operations of addition, multiplication (assumed to be associative), and a scalar multiplication by elements in some field.

New!!: General topology and Associative algebra · See more »

Axiom of countable choice

The axiom of countable choice or axiom of denumerable choice, denoted ACω, is an axiom of set theory that states that every countable collection of non-empty sets must have a choice function.

New!!: General topology and Axiom of countable choice · See more »

Baire category theorem

The Baire category theorem (BCT) is an important tool in general topology and functional analysis.

New!!: General topology and Baire category theorem · See more »

Baire space

In mathematics, a Baire space is a topological space such that every intersection of a countable collection of open dense sets in the space is also dense.

New!!: General topology and Baire space · See more »

Ball (mathematics)

In mathematics, a ball is the space bounded by a sphere.

New!!: General topology and Ball (mathematics) · See more »

Base (topology)

In mathematics, a base (or basis) B for a topological space X with topology T is a collection of open sets in T such that every open set in T can be written as a union of elements of B.We are using a convention that the union of empty collection of sets is the empty set.

New!!: General topology and Base (topology) · See more »

Bijection

In mathematics, a bijection, bijective function, or one-to-one correspondence is a function between the elements of two sets, where each element of one set is paired with exactly one element of the other set, and each element of the other set is paired with exactly one element of the first set.

New!!: General topology and Bijection · See more »

Boundary (topology)

In topology and mathematics in general, the boundary of a subset S of a topological space X is the set of points which can be approached both from S and from the outside of S. More precisely, it is the set of points in the closure of S not belonging to the interior of S. An element of the boundary of S is called a boundary point of S. The term boundary operation refers to finding or taking the boundary of a set.

New!!: General topology and Boundary (topology) · See more »

Box topology

In topology, the cartesian product of topological spaces can be given several different topologies.

New!!: General topology and Box topology · See more »

Category (mathematics)

In mathematics, a category (sometimes called an abstract category to distinguish it from a concrete category) is an algebraic structure similar to a group but without requiring inverse or closure properties.

New!!: General topology and Category (mathematics) · See more »

Category of topological spaces

In mathematics, the category of topological spaces, often denoted Top, is the category whose objects are topological spaces and whose morphisms are continuous maps or some other variant; for example, objects are often assumed to be compactly generated.

New!!: General topology and Category of topological spaces · See more »

Characterizations of the category of topological spaces

In mathematics, a topological space is usually defined in terms of open sets.

New!!: General topology and Characterizations of the category of topological spaces · See more »

Clopen set

In topology, a clopen set (a portmanteau of closed-open set) in a topological space is a set which is both open and closed.

New!!: General topology and Clopen set · See more »

Closed set

In geometry, topology, and related branches of mathematics, a closed set is a set whose complement is an open set.

New!!: General topology and Closed set · See more »

Closure (topology)

In mathematics, the closure of a subset S of points in a topological space consists of all points in S together with all limit points of S. The closure of S may equivalently be defined as the union of S and its boundary, and also as the intersection of all closed sets containing S. Intuitively, the closure can be thought of as all the points that are either in S or "near" S. A point which is in the closure of S is a point of closure of S. The notion of closure is in many ways dual to the notion of interior.

New!!: General topology and Closure (topology) · See more »

Closure operator

In mathematics, a closure operator on a set S is a function \operatorname: \mathcal(S)\rightarrow \mathcal(S) from the power set of S to itself which satisfies the following conditions for all sets X,Y\subseteq S |- | X \subseteq \operatorname(X) | (cl is extensive) |- | X\subseteq Y \Rightarrow \operatorname(X) \subseteq \operatorname(Y) | (cl is increasing) |- | \operatorname(\operatorname(X)).

New!!: General topology and Closure operator · See more »

Cocountable topology

The cocountable topology or countable complement topology on any set X consists of the empty set and all cocountable subsets of X, that is all sets whose complement in X is countable.

New!!: General topology and Cocountable topology · See more »

Codomain

In mathematics, the codomain or target set of a function is the set into which all of the output of the function is constrained to fall.

New!!: General topology and Codomain · See more »

Cofiniteness

In mathematics, a cofinite subset of a set X is a subset A whose complement in X is a finite set.

New!!: General topology and Cofiniteness · See more »

Compact space

In mathematics, and more specifically in general topology, compactness is a property that generalizes the notion of a subset of Euclidean space being closed (that is, containing all its limit points) and bounded (that is, having all its points lie within some fixed distance of each other).

New!!: General topology and Compact space · See more »

Comparison of topologies

In topology and related areas of mathematics, the set of all possible topologies on a given set forms a partially ordered set.

New!!: General topology and Comparison of topologies · See more »

Complement (set theory)

In set theory, the complement of a set refers to elements not in.

New!!: General topology and Complement (set theory) · See more »

Complete metric space

In mathematical analysis, a metric space M is called complete (or a Cauchy space) if every Cauchy sequence of points in M has a limit that is also in M or, alternatively, if every Cauchy sequence in M converges in M. Intuitively, a space is complete if there are no "points missing" from it (inside or at the boundary).

New!!: General topology and Complete metric space · See more »

Complex number

A complex number is a number that can be expressed in the form, where and are real numbers, and is a solution of the equation.

New!!: General topology and Complex number · See more »

Connected space

In topology and related branches of mathematics, a connected space is a topological space that cannot be represented as the union of two or more disjoint nonempty open subsets.

New!!: General topology and Connected space · See more »

Connectedness

In mathematics, connectedness is used to refer to various properties meaning, in some sense, "all one piece".

New!!: General topology and Connectedness · See more »

Continuous function

In mathematics, a continuous function is a function for which sufficiently small changes in the input result in arbitrarily small changes in the output.

New!!: General topology and Continuous function · See more »

Countable set

In mathematics, a countable set is a set with the same cardinality (number of elements) as some subset of the set of natural numbers.

New!!: General topology and Countable set · See more »

Counterexamples in Topology

Counterexamples in Topology (1970, 2nd ed. 1978) is a book on mathematics by topologists Lynn Steen and J. Arthur Seebach, Jr. In the process of working on problems like the metrization problem, topologists (including Steen and Seebach) have defined a wide variety of topological properties.

New!!: General topology and Counterexamples in Topology · See more »

Cover (topology)

In mathematics, a cover of a set X is a collection of sets whose union contains X as a subset.

New!!: General topology and Cover (topology) · See more »

Cylinder set

In mathematics, a cylinder set is the natural set in a product space.

New!!: General topology and Cylinder set · See more »

David van Dantzig

David van Dantzig (September 23, 1900 – July 22, 1959) was a Dutch mathematician, well known for the construction in topology of the dyadic solenoid.

New!!: General topology and David van Dantzig · See more »

David Van Nostrand

David Van Nostrand (December 5, 1811, New York City – June 14, 1886, New York City) was a New York City publisher.

New!!: General topology and David Van Nostrand · See more »

Dense set

In topology and related areas of mathematics, a subset A of a topological space X is called dense (in X) if every point x in X either belongs to A or is a limit point of A, that is the closure of A is constituting the whole set X. Informally, for every point in X, the point is either in A or arbitrarily "close" to a member of A — for instance, every real number either is a rational number or has a rational number arbitrarily close to it (see Diophantine approximation).

New!!: General topology and Dense set · See more »

Differential topology

In mathematics, differential topology is the field dealing with differentiable functions on differentiable manifolds.

New!!: General topology and Differential topology · See more »

Directed set

In mathematics, a directed set (or a directed preorder or a filtered set) is a nonempty set A together with a reflexive and transitive binary relation ≤ (that is, a preorder), with the additional property that every pair of elements has an upper bound.

New!!: General topology and Directed set · See more »

Discrete space

In topology, a discrete space is a particularly simple example of a topological space or similar structure, one in which the points form a discontinuous sequence, meaning they are isolated from each other in a certain sense.

New!!: General topology and Discrete space · See more »

Disjoint sets

In mathematics, two sets are said to be disjoint sets if they have no element in common.

New!!: General topology and Disjoint sets · See more »

Domain of a function

In mathematics, and more specifically in naive set theory, the domain of definition (or simply the domain) of a function is the set of "input" or argument values for which the function is defined.

New!!: General topology and Domain of a function · See more »

Dover Publications

Dover Publications, also known as Dover Books, is an American book publisher founded in 1941 by Hayward Cirker and his wife, Blanche.

New!!: General topology and Dover Publications · See more »

Duality (mathematics)

In mathematics, a duality, generally speaking, translates concepts, theorems or mathematical structures into other concepts, theorems or structures, in a one-to-one fashion, often (but not always) by means of an involution operation: if the dual of A is B, then the dual of B is A. Such involutions sometimes have fixed points, so that the dual of A is A itself.

New!!: General topology and Duality (mathematics) · See more »

Empty set

In mathematics, and more specifically set theory, the empty set or null set is the unique set having no elements; its size or cardinality (count of elements in a set) is zero.

New!!: General topology and Empty set · See more »

Equivalence class

In mathematics, when the elements of some set S have a notion of equivalence (formalized as an equivalence relation) defined on them, then one may naturally split the set S into equivalence classes.

New!!: General topology and Equivalence class · See more »

Equivalence relation

In mathematics, an equivalence relation is a binary relation that is reflexive, symmetric and transitive.

New!!: General topology and Equivalence relation · See more »

Euclidean space

In geometry, Euclidean space encompasses the two-dimensional Euclidean plane, the three-dimensional space of Euclidean geometry, and certain other spaces.

New!!: General topology and Euclidean space · See more »

Family of sets

In set theory and related branches of mathematics, a collection F of subsets of a given set S is called a family of subsets of S, or a family of sets over S. More generally, a collection of any sets whatsoever is called a family of sets.

New!!: General topology and Family of sets · See more »

Final topology

In general topology and related areas of mathematics, the final topology (or strong, colimit, coinduced, or inductive topology) on a set X, with respect to a family of functions into X, is the finest topology on X which makes those functions continuous.

New!!: General topology and Final topology · See more »

Finite set

In mathematics, a finite set is a set that has a finite number of elements.

New!!: General topology and Finite set · See more »

Finite topological space

In mathematics, a finite topological space is a topological space for which the underlying point set is finite.

New!!: General topology and Finite topological space · See more »

First-countable space

In topology, a branch of mathematics, a first-countable space is a topological space satisfying the "first axiom of countability".

New!!: General topology and First-countable space · See more »

Fréchet space

In functional analysis and related areas of mathematics, Fréchet spaces, named after Maurice Fréchet, are special topological vector spaces.

New!!: General topology and Fréchet space · See more »

Function (mathematics)

In mathematics, a function was originally the idealization of how a varying quantity depends on another quantity.

New!!: General topology and Function (mathematics) · See more »

Functional analysis

Functional analysis is a branch of mathematical analysis, the core of which is formed by the study of vector spaces endowed with some kind of limit-related structure (e.g. inner product, norm, topology, etc.) and the linear functions defined on these spaces and respecting these structures in a suitable sense.

New!!: General topology and Functional analysis · See more »

Geometric topology

In mathematics, geometric topology is the study of manifolds and maps between them, particularly embeddings of one manifold into another.

New!!: General topology and Geometric topology · See more »

George F. Simmons

George Finlay Simmons (born 1925) is an American mathematician who worked in topology and classical analysis.

New!!: General topology and George F. Simmons · See more »

Glossary of topology

This is a glossary of some terms used in the branch of mathematics known as topology.

New!!: General topology and Glossary of topology · See more »

Graph theory

In mathematics, graph theory is the study of graphs, which are mathematical structures used to model pairwise relations between objects.

New!!: General topology and Graph theory · See more »

Hausdorff space

In topology and related branches of mathematics, a Hausdorff space, separated space or T2 space is a topological space in which distinct points have disjoint neighbourhoods.

New!!: General topology and Hausdorff space · See more »

Heine–Borel theorem

In real analysis the Heine–Borel theorem, named after Eduard Heine and Émile Borel, states: For a subset S of Euclidean space Rn, the following two statements are equivalent.

New!!: General topology and Heine–Borel theorem · See more »

History of the separation axioms

The history of the separation axioms in general topology has been convoluted, with many meanings competing for the same terms and many terms competing for the same concept.

New!!: General topology and History of the separation axioms · See more »

Homeomorphism

In the mathematical field of topology, a homeomorphism or topological isomorphism or bi continuous function is a continuous function between topological spaces that has a continuous inverse function.

New!!: General topology and Homeomorphism · See more »

Identity function

Graph of the identity function on the real numbers In mathematics, an identity function, also called an identity relation or identity map or identity transformation, is a function that always returns the same value that was used as its argument.

New!!: General topology and Identity function · See more »

Identity of indiscernibles

The identity of indiscernibles is an ontological principle that states that there cannot be separate objects or entities that have all their properties in common.

New!!: General topology and Identity of indiscernibles · See more »

If and only if

In logic and related fields such as mathematics and philosophy, if and only if (shortened iff) is a biconditional logical connective between statements.

New!!: General topology and If and only if · See more »

Image (mathematics)

In mathematics, an image is the subset of a function's codomain which is the output of the function from a subset of its domain.

New!!: General topology and Image (mathematics) · See more »

Index set

In mathematics, an index set is a set whose members label (or index) members of another set.

New!!: General topology and Index set · See more »

Indexed family

In mathematics, an indexed family is informally a collection of objects, each associated with an index from some index set.

New!!: General topology and Indexed family · See more »

Initial topology

In general topology and related areas of mathematics, the initial topology (or weak topology or limit topology or projective topology) on a set X, with respect to a family of functions on X, is the coarsest topology on X that makes those functions continuous.

New!!: General topology and Initial topology · See more »

Interior (topology)

In mathematics, specifically in topology, the interior of a subset S of points of a topological space X consists of all points of S that do not belong to the boundary of S. A point that is in the interior of S is an interior point of S. The interior of S is the complement of the closure of the complement of S. In this sense interior and closure are dual notions.

New!!: General topology and Interior (topology) · See more »

Internet Archive

The Internet Archive is a San Francisco–based nonprofit digital library with the stated mission of "universal access to all knowledge." It provides free public access to collections of digitized materials, including websites, software applications/games, music, movies/videos, moving images, and nearly three million public-domain books.

New!!: General topology and Internet Archive · See more »

Intersection (set theory)

In mathematics, the intersection A ∩ B of two sets A and B is the set that contains all elements of A that also belong to B (or equivalently, all elements of B that also belong to A), but no other elements.

New!!: General topology and Intersection (set theory) · See more »

Interval (mathematics)

In mathematics, a (real) interval is a set of real numbers with the property that any number that lies between two numbers in the set is also included in the set.

New!!: General topology and Interval (mathematics) · See more »

Inverse function

In mathematics, an inverse function (or anti-function) is a function that "reverses" another function: if the function applied to an input gives a result of, then applying its inverse function to gives the result, and vice versa.

New!!: General topology and Inverse function · See more »

James Munkres

James Raymond Munkres (born August 18, 1930) is a Professor Emeritus of mathematics at MIT and the author of several texts in the area of topology, including Topology (an undergraduate-level text), Analysis on Manifolds, Elements of Algebraic Topology, and Elementary Differential Topology.

New!!: General topology and James Munkres · See more »

John L. Kelley

John L. Kelley (December 6, 1916, Kansas – November 26, 1999, Berkeley, California) was an American mathematician at University of California, Berkeley who worked in general topology and functional analysis.

New!!: General topology and John L. Kelley · See more »

John von Neumann

John von Neumann (Neumann János Lajos,; December 28, 1903 – February 8, 1957) was a Hungarian-American mathematician, physicist, computer scientist, and polymath.

New!!: General topology and John von Neumann · See more »

Kolmogorov space

In topology and related branches of mathematics, a topological space X is a T0 space or Kolmogorov space (named after Andrey Kolmogorov) if for every pair of distinct points of X, at least one of them has a neighborhood not containing the other.

New!!: General topology and Kolmogorov space · See more »

Kuratowski closure axioms

In topology and related branches of mathematics, the Kuratowski closure axioms are a set of axioms that can be used to define a topological structure on a set.

New!!: General topology and Kuratowski closure axioms · See more »

Limit of a sequence

As the positive integer n becomes larger and larger, the value n\cdot \sin\bigg(\frac1\bigg) becomes arbitrarily close to 1.

New!!: General topology and Limit of a sequence · See more »

Limit point

In mathematics, a limit point (or cluster point or accumulation point) of a set S in a topological space X is a point x that can be "approximated" by points of S in the sense that every neighbourhood of x with respect to the topology on X also contains a point of S other than x itself.

New!!: General topology and Limit point · See more »

Lindelöf space

In mathematics, a Lindelöf space is a topological space in which every open cover has a countable subcover.

New!!: General topology and Lindelöf space · See more »

Linear map

In mathematics, a linear map (also called a linear mapping, linear transformation or, in some contexts, linear function) is a mapping between two modules (including vector spaces) that preserves (in the sense defined below) the operations of addition and scalar multiplication.

New!!: General topology and Linear map · See more »

List of examples in general topology

This is a list of useful examples in general topology, a field of mathematics.

New!!: General topology and List of examples in general topology · See more »

List of general topology topics

This is a list of general topology topics, by Wikipedia page.

New!!: General topology and List of general topology topics · See more »

Local field

In mathematics, a local field is a special type of field that is a locally compact topological field with respect to a non-discrete topology.

New!!: General topology and Local field · See more »

Locally compact space

In topology and related branches of mathematics, a topological space is called locally compact if, roughly speaking, each small portion of the space looks like a small portion of a compact space.

New!!: General topology and Locally compact space · See more »

Locally connected space

In topology and other branches of mathematics, a topological space X is locally connected if every point admits a neighbourhood basis consisting entirely of open, connected sets.

New!!: General topology and Locally connected space · See more »

Long line (topology)

In topology, the long line (or Alexandroff line) is a topological space somewhat similar to the real line, but in a certain way "longer".

New!!: General topology and Long line (topology) · See more »

Lower limit topology

In mathematics, the lower limit topology or right half-open interval topology is a topology defined on the set \mathbb of real numbers; it is different from the standard topology on \mathbb (generated by the open intervals) and has a number of interesting properties.

New!!: General topology and Lower limit topology · See more »

Manifold

In mathematics, a manifold is a topological space that locally resembles Euclidean space near each point.

New!!: General topology and Manifold · See more »

Mathematical object

A mathematical object is an abstract object arising in mathematics.

New!!: General topology and Mathematical object · See more »

Mathematics

Mathematics (from Greek μάθημα máthēma, "knowledge, study, learning") is the study of such topics as quantity, structure, space, and change.

New!!: General topology and Mathematics · See more »

Maurice René Fréchet

Maurice Fréchet (2 September 1878 – 4 June 1973) was a French mathematician.

New!!: General topology and Maurice René Fréchet · See more »

Maximal and minimal elements

In mathematics, especially in order theory, a maximal element of a subset S of some partially ordered set (poset) is an element of S that is not smaller than any other element in S. A minimal element of a subset S of some partially ordered set is defined dually as an element of S that is not greater than any other element in S. The notions of maximal and minimal elements are weaker than those of greatest element and least element which are also known, respectively, as maximum and minimum.

New!!: General topology and Maximal and minimal elements · See more »

Mereotopology

In formal ontology, a branch of metaphysics, and in ontological computer science, mereotopology is a first-order theory, embodying mereological and topological concepts, of the relations among wholes, parts, parts of parts, and the boundaries between parts.

New!!: General topology and Mereotopology · See more »

Metric (mathematics)

In mathematics, a metric or distance function is a function that defines a distance between each pair of elements of a set.

New!!: General topology and Metric (mathematics) · See more »

Metric space

In mathematics, a metric space is a set for which distances between all members of the set are defined.

New!!: General topology and Metric space · See more »

Metrization theorem

In topology and related areas of mathematics, a metrizable space is a topological space that is homeomorphic to a metric space.

New!!: General topology and Metrization theorem · See more »

Natural topology

In any domain of mathematics, a space has a natural topology if there is a topology on the space which is "best adapted" to its study within the domain in question.

New!!: General topology and Natural topology · See more »

Necessity and sufficiency

In logic, necessity and sufficiency are terms used to describe an implicational relationship between statements.

New!!: General topology and Necessity and sufficiency · See more »

Neighbourhood (mathematics)

In topology and related areas of mathematics, a neighbourhood (or neighborhood) is one of the basic concepts in a topological space.

New!!: General topology and Neighbourhood (mathematics) · See more »

Neighbourhood system

In topology and related areas of mathematics, the neighbourhood system, complete system of neighbourhoods, or neighbourhood filter \mathcal(x) for a point x is the collection of all neighbourhoods for the point x.

New!!: General topology and Neighbourhood system · See more »

Net (mathematics)

In mathematics, more specifically in general topology and related branches, a net or Moore–Smith sequence is a generalization of the notion of a sequence.

New!!: General topology and Net (mathematics) · See more »

Nicolas Bourbaki

Nicolas Bourbaki is the collective pseudonym under which a group of (mainly French) 20th-century mathematicians, with the aim of reformulating mathematics on an extremely abstract and formal but self-contained basis, wrote a series of books beginning in 1935.

New!!: General topology and Nicolas Bourbaki · See more »

Normal space

In topology and related branches of mathematics, a normal space is a topological space X that satisfies Axiom T4: every two disjoint closed sets of X have disjoint open neighborhoods.

New!!: General topology and Normal space · See more »

Normed vector space

In mathematics, a normed vector space is a vector space over the real or complex numbers, on which a norm is defined.

New!!: General topology and Normed vector space · See more »

Nowhere dense set

In mathematics, a nowhere dense set on a topological space is a set whose closure has empty interior.

New!!: General topology and Nowhere dense set · See more »

Open and closed maps

In topology, an open map is a function between two topological spaces which maps open sets to open sets.

New!!: General topology and Open and closed maps · See more »

Open set

In topology, an open set is an abstract concept generalizing the idea of an open interval in the real line.

New!!: General topology and Open set · See more »

Order topology

In mathematics, an order topology is a certain topology that can be defined on any totally ordered set.

New!!: General topology and Order topology · See more »

Ordered pair

In mathematics, an ordered pair (a, b) is a pair of objects.

New!!: General topology and Ordered pair · See more »

Ordinal number

In set theory, an ordinal number, or ordinal, is one generalization of the concept of a natural number that is used to describe a way to arrange a collection of objects in order, one after another.

New!!: General topology and Ordinal number · See more »

Paracompact space

In mathematics, a paracompact space is a topological space in which every open cover has an open refinement that is locally finite.

New!!: General topology and Paracompact space · See more »

Partially ordered set

In mathematics, especially order theory, a partially ordered set (also poset) formalizes and generalizes the intuitive concept of an ordering, sequencing, or arrangement of the elements of a set.

New!!: General topology and Partially ordered set · See more »

Partition of a set

In mathematics, a partition of a set is a grouping of the set's elements into non-empty subsets, in such a way that every element is included in one and only one of the subsets.

New!!: General topology and Partition of a set · See more »

Path (topology)

In mathematics, a path in a topological space X is a continuous function f from the unit interval I.

New!!: General topology and Path (topology) · See more »

Path graph

In the mathematical field of graph theory, a path graph or linear graph is a graph whose vertices can be listed in the order v1, v2, …, vn such that the edges are where i.

New!!: General topology and Path graph · See more »

Point (geometry)

In modern mathematics, a point refers usually to an element of some set called a space.

New!!: General topology and Point (geometry) · See more »

Polynomial

In mathematics, a polynomial is an expression consisting of variables (also called indeterminates) and coefficients, that involves only the operations of addition, subtraction, multiplication, and non-negative integer exponents of variables.

New!!: General topology and Polynomial · See more »

Product topology

In topology and related areas of mathematics, a product space is the cartesian product of a family of topological spaces equipped with a natural topology called the product topology.

New!!: General topology and Product topology · See more »

Projection (mathematics)

In mathematics, a projection is a mapping of a set (or other mathematical structure) into a subset (or sub-structure), which is equal to its square for mapping composition (or, in other words, which is idempotent).

New!!: General topology and Projection (mathematics) · See more »

Projection (set theory)

In set theory, a projection is one of two closely related types of functions or operations, namely.

New!!: General topology and Projection (set theory) · See more »

Property

Property, in the abstract, is what belongs to or with something, whether as an attribute or as a component of said thing.

New!!: General topology and Property · See more »

Quotient space (topology)

In topology and related areas of mathematics, a quotient space (also called an identification space) is, intuitively speaking, the result of identifying or "gluing together" certain points of a given topological space.

New!!: General topology and Quotient space (topology) · See more »

Rational number

In mathematics, a rational number is any number that can be expressed as the quotient or fraction of two integers, a numerator and a non-zero denominator.

New!!: General topology and Rational number · See more »

Real line

In mathematics, the real line, or real number line is the line whose points are the real numbers.

New!!: General topology and Real line · See more »

Real number

In mathematics, a real number is a value of a continuous quantity that can represent a distance along a line.

New!!: General topology and Real number · See more »

Regular space

In topology and related fields of mathematics, a topological space X is called a regular space if every closed subset C of X and a point p not contained in C admit non-overlapping open neighborhoods.

New!!: General topology and Regular space · See more »

Ryszard Engelking

Ryszard Engelking (born 1935 in Sosnowiec) is a Polish mathematician.

New!!: General topology and Ryszard Engelking · See more »

Second-countable space

In topology, a second-countable space, also called a completely separable space, is a topological space whose topology has a countable base.

New!!: General topology and Second-countable space · See more »

Separable space

In mathematics, a topological space is called separable if it contains a countable, dense subset; that is, there exists a sequence \_^ of elements of the space such that every nonempty open subset of the space contains at least one element of the sequence.

New!!: General topology and Separable space · See more »

Separated sets

In topology and related branches of mathematics, separated sets are pairs of subsets of a given topological space that are related to each other in a certain way: roughly speaking, neither overlapping nor touching.

New!!: General topology and Separated sets · See more »

Sequence

In mathematics, a sequence is an enumerated collection of objects in which repetitions are allowed.

New!!: General topology and Sequence · See more »

Sequential space

In topology and related fields of mathematics, a sequential space is a topological space that satisfies a very weak axiom of countability.

New!!: General topology and Sequential space · See more »

Set theory

Set theory is a branch of mathematical logic that studies sets, which informally are collections of objects.

New!!: General topology and Set theory · See more »

Sierpiński space

In mathematics, the Sierpiński space (or the connected two-point set) is a finite topological space with two points, only one of which is closed.

New!!: General topology and Sierpiński space · See more »

Simplex

In geometry, a simplex (plural: simplexes or simplices) is a generalization of the notion of a triangle or tetrahedron to arbitrary dimensions.

New!!: General topology and Simplex · See more »

Simplicial complex

In mathematics, a simplicial complex is a set composed of points, line segments, triangles, and their ''n''-dimensional counterparts (see illustration).

New!!: General topology and Simplicial complex · See more »

Solution set

In mathematics, a solution set is the set of values that satisfy a given set of equations or inequalities.

New!!: General topology and Solution set · See more »

Spectrum of a ring

In abstract algebra and algebraic geometry, the spectrum of a commutative ring R, denoted by \operatorname(R), is the set of all prime ideals of R. It is commonly augmented with the Zariski topology and with a structure sheaf, turning it into a locally ringed space.

New!!: General topology and Spectrum of a ring · See more »

Springer Science+Business Media

Springer Science+Business Media or Springer, part of Springer Nature since 2015, is a global publishing company that publishes books, e-books and peer-reviewed journals in science, humanities, technical and medical (STM) publishing.

New!!: General topology and Springer Science+Business Media · See more »

Stephen Willard

Stephen Willard (born 27 August 1958) is a professional English darts player who plays in British Darts Organisation events.

New!!: General topology and Stephen Willard · See more »

Subbase

In topology, a subbase (or subbasis) for a topological space with topology is a subcollection of that generates, in the sense that is the smallest topology containing.

New!!: General topology and Subbase · See more »

Subset

In mathematics, a set A is a subset of a set B, or equivalently B is a superset of A, if A is "contained" inside B, that is, all elements of A are also elements of B. A and B may coincide.

New!!: General topology and Subset · See more »

Subspace topology

In topology and related areas of mathematics, a subspace of a topological space X is a subset S of X which is equipped with a topology induced from that of X called the subspace topology (or the relative topology, or the induced topology, or the trace topology).

New!!: General topology and Subspace topology · See more »

Surjective function

In mathematics, a function f from a set X to a set Y is surjective (or onto), or a surjection, if for every element y in the codomain Y of f there is at least one element x in the domain X of f such that f(x).

New!!: General topology and Surjective function · See more »

T1 space

In topology and related branches of mathematics, a T1 space is a topological space in which, for every pair of distinct points, each has a neighborhood not containing the other.

New!!: General topology and T1 space · See more »

Theorem

In mathematics, a theorem is a statement that has been proven on the basis of previously established statements, such as other theorems, and generally accepted statements, such as axioms.

New!!: General topology and Theorem · See more »

Theory of computation

In theoretical computer science and mathematics, the theory of computation is the branch that deals with how efficiently problems can be solved on a model of computation, using an algorithm.

New!!: General topology and Theory of computation · See more »

Thesis

A thesis or dissertation is a document submitted in support of candidature for an academic degree or professional qualification presenting the author's research and findings.

New!!: General topology and Thesis · See more »

Tietze extension theorem

In topology, the Tietze extension theorem (also known as the Tietze–Urysohn–Brouwer extension theorem) states that continuous functions on a closed subset of a normal topological space can be extended to the entire space, preserving boundedness if necessary.

New!!: General topology and Tietze extension theorem · See more »

Topological indistinguishability

In topology, two points of a topological space X are topologically indistinguishable if they have exactly the same neighborhoods.

New!!: General topology and Topological indistinguishability · See more »

Topological ring

In mathematics, a topological ring is a ring R which is also a topological space such that both the addition and the multiplication are continuous as maps where R × R carries the product topology.

New!!: General topology and Topological ring · See more »

Topological space

In topology and related branches of mathematics, a topological space may be defined as a set of points, along with a set of neighbourhoods for each point, satisfying a set of axioms relating points and neighbourhoods.

New!!: General topology and Topological space · See more »

Topological vector space

In mathematics, a topological vector space (also called a linear topological space) is one of the basic structures investigated in functional analysis.

New!!: General topology and Topological vector space · See more »

Topologist's sine curve

In the branch of mathematics known as topology, the topologist's sine curve or Warsaw sine curve is a topological space with several interesting properties that make it an important textbook example.

New!!: General topology and Topologist's sine curve · See more »

Topology

In mathematics, topology (from the Greek τόπος, place, and λόγος, study) is concerned with the properties of space that are preserved under continuous deformations, such as stretching, crumpling and bending, but not tearing or gluing.

New!!: General topology and Topology · See more »

Totally disconnected space

In topology and related branches of mathematics, a totally disconnected space is a topological space that is maximally disconnected, in the sense that it has no non-trivial connected subsets.

New!!: General topology and Totally disconnected space · See more »

Triangle inequality

In mathematics, the triangle inequality states that for any triangle, the sum of the lengths of any two sides must be greater than or equal to the length of the remaining side.

New!!: General topology and Triangle inequality · See more »

Trivial topology

In topology, a topological space with the trivial topology is one where the only open sets are the empty set and the entire space.

New!!: General topology and Trivial topology · See more »

Tychonoff space

In topology and related branches of mathematics, Tychonoff spaces and completely regular spaces are kinds of topological spaces.

New!!: General topology and Tychonoff space · See more »

Tychonoff's theorem

In mathematics, Tychonoff's theorem states that the product of any collection of compact topological spaces is compact with respect to the product topology.

New!!: General topology and Tychonoff's theorem · See more »

Union (set theory)

In set theory, the union (denoted by ∪) of a collection of sets is the set of all elements in the collection.

New!!: General topology and Union (set theory) · See more »

Unit interval

In mathematics, the unit interval is the closed interval, that is, the set of all real numbers that are greater than or equal to 0 and less than or equal to 1.

New!!: General topology and Unit interval · See more »

Urysohn and completely Hausdorff spaces

In topology, a discipline within mathematics, an Urysohn space, or T2½ space, is a topological space in which any two distinct points can be separated by closed neighborhoods.

New!!: General topology and Urysohn and completely Hausdorff spaces · See more »

Urysohn's lemma

In topology, Urysohn's lemma is a lemma that states that a topological space is normal if and only if any two disjoint closed subsets can be separated by a continuous function.

New!!: General topology and Urysohn's lemma · See more »

Vector space

A vector space (also called a linear space) is a collection of objects called vectors, which may be added together and multiplied ("scaled") by numbers, called scalars.

New!!: General topology and Vector space · See more »

Vertex (graph theory)

In mathematics, and more specifically in graph theory, a vertex (plural vertices) or node is the fundamental unit of which graphs are formed: an undirected graph consists of a set of vertices and a set of edges (unordered pairs of vertices), while a directed graph consists of a set of vertices and a set of arcs (ordered pairs of vertices).

New!!: General topology and Vertex (graph theory) · See more »

Zariski topology

In algebraic geometry and commutative algebra, the Zariski topology is a topology on algebraic varieties, introduced primarily by Oscar Zariski and later generalized for making the set of prime ideals of a commutative ring a topological space, called the spectrum of the ring.

New!!: General topology and Zariski topology · See more »

(ε, δ)-definition of limit

In calculus, the (ε, δ)-definition of limit ("epsilon–delta definition of limit") is a formalization of the notion of limit.

New!!: General topology and (ε, δ)-definition of limit · See more »

Redirects here:

Basic topology, Introduction to topology, Introductory topology, Point set space, Point set topology, Point-set theory, Point-set topology.

References

[1] https://en.wikipedia.org/wiki/General_topology

OutgoingIncoming
Hey! We are on Facebook now! »