A.T. Fomenko, Double cover of the Klein bottle by torus
Pasha Zusmanovich

6TOPO Topology, winter semester 2023/2024

Teams

LITERATURE
Main: Additional: All the books are available in electronic form in multiple places.          = available in the university library

A BRIEF SYNOPSIS
(Each class lasted approximately 1.5 hours if not specified otherwise)

Class 1 September 19, 2023
Organizational details. The subject of topology. Definition of a topological space. Examples of topological spaces: trivial and discrete toplogy, topologies on 0-, 1- and 2-element sets, the standard topology on \(\mathbb R\), the arrow. Number of topologies on a finite set. ([V], pp. xi-xii, 2, 11-12; Munkres, p.76).

Class 2 September 26, 2023
Closed sets. Clopen sets. A parody of an episode from the movie "The Bunker" featuring clopen sets. Cantor set as an example of a closed set. Definition of topology in terms of closed sets. Base of a topology. The standard topology on \(\mathbb R\) does not have a minimal base. ([V], pp.13-16).

Class 3 October 4, 2023
Criteria for a set of subsets to be a base ([V],p.16,3.A,3.B,3.C). Bases of the standard topology on \(\mathbb R^2\). Criterion for two bases to be equivalent. Finer and coarser topologies. ([V], pp.16-17; Munkres, p.81).

Class 4 October 11, 2023
Metric spaces. 0-1 metric, Euclidean metric, Manhattan metric. Restriction of a metric to a subspace. Balls and spheres. ([V], pp.18-20).

Class 5 November 3, 2023
Metric topology. Metrizability of topological spaces, examples of metrizable and non-metrizable spaces. Topological and metric equivalences of metrics. ([V], pp.22-23; Munkres, pp.119-121).

Class 6 November 8, 2023 (approx. 2h)
Metric equivalence implies topological equiavalence. If \(\rho\) is a metric, then \(\frac{\rho}{1+\rho}\) is topologically equivalent, but not necessary metrically equavalent, metric. ([V], pp.22-23; Munkres, pp.119-121). pdf TeX

Class 7 November 15, 2023 (approx. 2h)
Subspace topology, examples. Interior, closure, boundary. Definition of continuous and open (i.e., an image of an open set is open) maps. \(x \mapsto |x|\) is continuous but not open. Equivalent conditions for continuity. ([V], pp.27,29-31,59; Munkres, pp.88-90,102-105).

Class 8 November 22, 2023 (approx. 2h)
Continuity at a point. Equivalence of topological definition of continuity with the \(\varepsilon-\delta\) definiton from analysis in the case of metric topologies. Homeomorphisms (definition, elementary properties). ([V], pp.61,67; Munkres, p.105).

Class 9 November 29, 2023 (approx. 2h40min)
Determining homeomorhisms of various topological spaces (trivial, discerete, cofinite topologies, some finite topology, arrow). Any two intervals on a line, considered as a subspace topologies of the standard topology, are homeomorphic. A semiopen interval is not homeomorphic to an open interval. ([V], pp.68-69).

Class 10 December 6, 2023 (approx. 2h30min)
Homeomorphisms of the arrow (redo). Further examples and non-examples of homeomorphisms. ([V], pp.69-73).

Class 11 December 13, 2023 (approx. 2h)
Homeomorphism and non-homeomorphism of planes with punctures (finishing). The product topology, examples. The quotient topology, examples. ([V], pp.72,136-137,141-143,145-148; Munkres, pp.86-87).


EXAM

Set 2: pdf TeX   Set 3: pdf TeX


A brief synopsis, videos, and homeworks from this course at the previous semesters


Created: Fri Oct 2 2020
Last modified: Wed Feb 28 06:42:23 CET 2024