What is Topological: Definition and 264 Discussions

In mathematics, topology (from the Greek words τόπος, 'place, location', and λόγος, 'study') is concerned with the properties of a geometric object that are preserved under continuous deformations, such as stretching, twisting, crumpling, and bending; that is, without closing holes, opening holes, tearing, gluing, or passing through itself.
A topological space is a set endowed with a structure, called a topology, which allows defining continuous deformation of subspaces, and, more generally, all kinds of continuity. Euclidean spaces, and, more generally, metric spaces are examples of a topological space, as any distance or metric defines a topology. The deformations that are considered in topology are homeomorphisms and homotopies. A property that is invariant under such deformations is a topological property. Basic examples of topological properties are: the dimension, which allows distinguishing between a line and a surface; compactness, which allows distinguishing between a line and a circle; connectedness, which allows distinguishing a circle from two non-intersecting circles.
The ideas underlying topology go back to Gottfried Leibniz, who in the 17th century envisioned the geometria situs and analysis situs. Leonhard Euler's Seven Bridges of Königsberg problem and polyhedron formula are arguably the field's first theorems. The term topology was introduced by Johann Benedict Listing in the 19th century, although it was not until the first decades of the 20th century that the idea of a topological space was developed.

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  1. P

    How can you tell if a specific topological space is compact?

    eddo's thread got me thinking: How can you tell if a specific topological space is compact? It seems like it would be hard to do just starting with the definition of compactness.
  2. E

    Proving Continuity of F:XxI->I with Continuous Functions

    How can I show that F:X\times I\to I given by F(x,t)=(1-t)f(x)+tg(x) is continuous, given that f:X\to I and g:X\to I are continuous (here I is the unit interval [0,1]). It seems that F is continuous, but I want to show that explicitly. Any help appreciated! X is any topological space. (I...
  3. wolram

    Exploring the Topological Origin of the Pioneer Anomaly

    http://lanl.arxiv.org/pdf/quant-ph/0501041 the pioneer anomaly is due to topological phase defect of light
  4. S

    Topological Unification of M-theory and LQG?

    I don't know if this paper was commented on here while I was away at Christmas time, but I was just pointed to it by a paper on today's arxiv and I think it desrves notice. http://arxiv.org/abs/hep-th/0411073 Robert Dijkgraaf, Sergei Gukov, Andrew Neitzke, and Cumrun Vafa; Toplogical...
  5. R

    Topology & Universe Evolution: Finite or Infinite Age?

    The critical density determines the Universe evolution along time. So, by measuring this density, we could know about the finite or infinite age of the Universe. But we don't know from General Relativity if our Universe is spatially finite or infinite. As far as I know, such question...
  6. J

    Chess/Math Puzzle: A Topological Approach

    This is a chess/math puzzle I invented: Consider a fully set up chess board (in starting position). Invent a condition (new rule) in which black wins without either side making any moves. Note: this problem has a really abstract and *topological* approach. :rofl: Please email me...
  7. humanino

    Quantum Charges for Knotted Topological Strings?

    I was wondering if knotted topological strings can be asigned definite quantum charges apart from mass and angular mumentum. That would really be useful to glueball people who try to find candidate in the hadronic spectrum : they use only mass and angular momentum. If they had a mean to assign...
  8. M

    Perfect Gen. Ordered Space Embeddable in Perfect Lin. Ordered Space

    Is it true that a perfect generalized ordered space can be embedded in a perfect linearly ordered space? It is true that a perfect generalized ordered space can be embedded as a closed subset in a perfect linearly ordered space.
  9. T

    Topological Defects in Cosmology: Research Progress

    What is topological defects in cosmology? Is this a current field of research and what are their progresses?
  10. M

    Hausdorff topological space M of dimension m

    I have printed a notes about differential geometry, and it says: -A Coo differentiable structure on a locally Euclidean, Hausdorff topological space M of dimension m is a collection of coordinate systems F Then it specifies the conditions that F must satisfy, but I'm a little lazy and won't...
  11. S

    Question on Topological Spaces

    I'm a noob starting out studying differential geometry and topology. Really probably somewhere in the multivariate calculus level, but I've been trying to understand the plethora of terminology I'm encountering with this higher math. I've been reading a lot on Wikipedia.org and PlanetMath.org...
  12. marcus

    Topological Quantum Field Theory, definition

    I believe that the Axioms for TQFT were set out by Atiyah in 1990 and that one of the equivalent definitions of a TQFT is in category terms: a TQFT is a functor from the category of n-dimensional cobordisms to the category of Hilbert spaces, satisfying certain conditions. Is anyone familiar...
  13. marcus

    Unifying general relativity with topological field theory

    From the abstract: "An action principle is described which unifies general relativity and topological field theory. An additional degree of freedom is introduced, and depending on the value it takes the theory has solutions that reduce it to (1) general relativity in the Palatini form, (2)...
  14. M

    Topological quantum field theories

    Chern-Simons theory is a 3d-TQFT and Crane-Yetter model is a 4d-TQFT There exist another Topological Quantum Field Theory apart of these two models?
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