In topology, a branch of mathematics, a subset E of a topological space X is said to be locally closed if the following equivalent conditions are met: * E is an intersection of an open subset and a closed subset of X. * For each point x in E, there is a neighborhood U of x in X such that is closed in U. * E is an open subset of the closure . The second condition justifies the terminology locally closed and is Bourbaki's definition of locally closed. To see the second condition implies the third, use the facts that for subsets , A is closed in B if and only if and that for a subset E and an open subset U, . Finite intersections and the pre-image under a continuous map of locally closed sets are locally closed. On the other hand, a union and a complement of locally closed subsets need not be locally closed. (This motivates the notion of a constructible set.) For example, is a locally closed subset of . For another example, consider the relative interior D of a closed disk in . It is locally closed since it is an intersection of the closed disk and an open ball. Recall that, by definition, a submanifold E of an n-manifold M is a subset such that for each point x in E, there is a chart around it such that . Hence, a submanifold is locally closed. For a locally closed subset E, the complement is called the boundary of E (not to be confused with topological boundary). If E is a closed submanifold-with-boundary of a manifold M, then the relative interior (i.e., interior as a manifold) of E is locally closed in M and the boundary of it as a manifold is the same as the boundary of it as a locally closed subset. A topological space is said to be submaximal if every subset is locally closed. See Glossary of topology#S for more of this notion. (Wikipedia).
Lecture with Ole Christensen. Kapitler: 00:00 - Def.: Closure Of A Subset; 06:45 - Dense Vs. Closure; 19:00 - Extension Of Operators On Dense Subspaces; 24:15 - Proof;
From playlist DTU: Mathematics 4 Real Analysis | CosmoLearning.org Math
Every Closed Subset of a Compact Space is Compact Proof
Every Closed Subset of a Compact Space is Compact Proof If you enjoyed this video please consider liking, sharing, and subscribing. You can also help support my channel by becoming a member https://www.youtube.com/channel/UCr7lmzIk63PZnBw3bezl-Mg/join Thank you:)
From playlist Topology
All About Closed Sets and Closures of Sets (and Clopen Sets) | Real Analysis
We introduced closed sets and clopen sets. We'll visit two definitions of closed sets. First, a set is closed if it is the complement of some open set, and second, a set is closed if it contains all of its limit points. We see examples of sets both closed and open (called "clopen sets") an
From playlist Real Analysis
Finding Closed Sets, the Closure of a Set, and Dense Subsets Topology
Please Subscribe here, thank you!!! https://goo.gl/JQ8Nys Finding Closed Sets, the Closure of a Set, and Dense Subsets Topology
From playlist Topology
Math subsets are an important concept to understand. So what is the subset definition in math? What is a subset? We go over that part of set theory in this video as well as some details on the empty set and its subset properties. Enjoy! I hope you find this video helpful, and be sure to a
From playlist Set Theory
15 Properties of partially ordered sets
When a relation induces a partial ordering of a set, that set has certain properties with respect to the reflexive, (anti)-symmetric, and transitive properties.
From playlist Abstract algebra
Math 101 Fall 2017 112917 Introduction to Compact Sets
Definition of an open cover. Definition of a compact set (in the real numbers). Examples and non-examples. Properties of compact sets: compact sets are bounded. Compact sets are closed. Closed subsets of compact sets are compact. Infinite subsets of compact sets have accumulation poi
From playlist Course 6: Introduction to Analysis (Fall 2017)
Every Compact Set in n space is Bounded
Every Compact Set in n space is Bounded If you enjoyed this video please consider liking, sharing, and subscribing. You can also help support my channel by becoming a member https://www.youtube.com/channel/UCr7lmzIk63PZnBw3bezl-Mg/join Thank you:)
From playlist Advanced Calculus
An Example of a Closed Continuous Function that is Not Open
An Example of a Closed Continuous Function that is Not Open If you enjoyed this video please consider liking, sharing, and subscribing. You can also help support my channel by becoming a member https://www.youtube.com/channel/UCr7lmzIk63PZnBw3bezl-Mg/join Thank you:)
From playlist Topology
Greg Stevenson: Tensor triangular geometry - Lecture 2
Tensor triangular geometry asks us to think of symmetric monoidal triangulated categories like rings, and in return provides us with an analogue of affine algebraic geometry. With this analogy in mind I'll introduce the general theory: starting with an essentially small symmetric monoidal
From playlist Summer School: Spectral methods in algebra, geometry, and topology
MAST30026 Lecture 12: Function spaces (Part 3)
We continued the discussion of the compact-open topology on function spaces. Guided by Part 2 we defined this topology, and got about half way through the proof that the adjunction property (aka the exponential law) holds when function spaces are given this topology. Lecture notes: http:/
From playlist MAST30026 Metric and Hilbert spaces
Local flexibility for open partial differential relations - Bernhard Hanke
Workshop on the h-principle and beyond Topic: Local flexibility for open partial differential relations Speaker: Bernhard Hanke Affiliation: University of Augsburg Date: November 1, 2021 Abstract: We discuss the problem of extending local deformations of solutions to open partial differ
From playlist Mathematics
Nero Budur: Absolute sets and the Decomposition Theorem
Abstract: We give a new, more conceptual proof of the Decomposition Theorem for semisimple perverse sheaves of rank-one origin, assuming it for those of constant-sheaf origin, that is, assuming the geometric case proven by Beilinson-Bernstein-Deligne-Gabber. Joint work with Botong Wang. R
From playlist Algebraic and Complex Geometry
This lecture is part of an online algebraic geometry course on schemes, based on chapter II of "Algebraic geometry" by Hartshorne. We define open and closed immersion, and give some basic properties and some examples.
From playlist Algebraic geometry II: Schemes
Lecture 7: Sheaves of sets (Part 2)
The most important examples of topoi are categories of sheaves of sets on a small category. Patrick Eilliott introduced this class of examples over two talks, of which is the second. In this talk he defines Grothendieck topologies and the category of sheaves on a site, and develops the exa
From playlist Topos theory seminar
José Manuel García-Calcines (6/24/21): Topological complexity using arbitrary covers
Title: Topological complexity using arbitrary covers
From playlist Topological Complexity Seminar
Sergey Melikhov, Steklov Math Institute (Moscow) Title: Fine Shape Abstract: A shape theory is something which is supposed to agree with homotopy theory on polyhedra and to treat more general spaces by looking at their polyhedral approximations. Or if you prefer, it is something which is s
From playlist 39th Annual Geometric Topology Workshop (Online), June 6-8, 2022
Local rigidity and C^0 symplectic and contact topology - Mike Usher
Symplectic Dynamics/Geometry Seminar Topic: Local rigidity and C^0 symplectic and contact topology Speaker: Mike Usher Affiliation: University of Georgia Date: November 11, 2019 For more video please visit http://video.ias.edu
From playlist Mathematics
E. Peyre - Slopes and distribution of points (part2)
The distribution of rational points of bounded height on algebraic varieties is far from uniform. Indeed the points tend to accumulate on thin subsets which are images of non-trivial finite morphisms. The problem is to find a way to characterise these thin subsets. The slopes introduced by
From playlist Ecole d'été 2017 - Géométrie d'Arakelov et applications diophantiennes
This video defines and give the notation used for subsets and proper subsets. http://mathispower4u.com
From playlist Sets