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# Topology - Continuum Theory

**DMS Continuum Theory Seminar**

Mar 19, 2018 05:00 PM

Parker Hall 228

Speaker: **Benjamin Vejnar** (Charles University, Prague)

Topic: The complexity of the homeomorphism equivalence relation on some classes of metrizable compacta with respect to Borel reducibility.

**DMS Topology Seminar**

Jan 31, 2018 02:00 PM

Parker Hall 246

Speaker: **Stu Baldwin**

Title: Inverse Limits of Flexagons

Abstract: Flexagons were first introduced in 1939 by Arthur H. Stone when he was a graduate student at Princeton, and they were popularized by Martin Gardner in the December 1956 issue of *Scientific American* in an article entitled "Flexagons" which launched his well known "Mathematical Games" column, which appeared in that magazine for many years. By folding strips of paper into various geometrical shapes, Stone created a variety of different flexagons, of which the most elegant are the "hexaflexagons" created by folding strips of equilateral triangles into a hexagonal shape and attaching the ends.

Mathematical studies of flexagons have concentrated on the combinatorial properties of flexagons created with a finite number of polygons. Here, we consider an infinite version which can be created either using inverse limits or nested intersections of solid tori (viewed as a folded annulus cross the unit interval). If $n \ge 3$, then a strip of $3n$ equilateral triangles can be folded into a hexaflexagon which (after the ends are identified) is topologically an annulus if $n$ is even and a Möbius strip if $n$ is odd. Of these, the most natural ones are created using $9(2^n)$ triangles, leading to the construction of a space (via either inverse limits or nested intersections) which (viewed as a subset of $\mathbb{R}^3$ in a natural way) mimics the properties of all of the hexaflexagons having finitely many triangles. Some preliminary results on the properties of this space will be discussed.

(Paper toys will be provided to the audience as visual aids.)

**Continuum Theory Seminar**

Feb 22, 2016 04:00 PM

Parker Hall 224

**Piotr Minc**will continue today talking about compactifications of the ray.

**Continuum Theory Seminar**

Feb 15, 2016 04:00 PM

Parker Hall 224

**Piotr Minc**will talk today about the work he’s done on certain compactifications for METRIC spaces.

**Continuum Theory Seminar**

Feb 08, 2016 04:00 PM

Parker Hall 224

**Michel Smith**will continue (and possibly conclude) his presentation on the non-metric pseudo-arc

**Continuum Theory Seminar**

Feb 01, 2016 04:00 PM

Parker Hall 224

Speaker: **Michel Smith**

Topic: some properties of the non-metric pseudo-arc relevant to the Wood’s Conjecture

**Continuum Theory Seminar**

Jan 25, 2016 04:00 PM

Parker Hall 224

Speakers: **Michel Smith**

Topic: joint work with Jan Boronski--pseudo-circle and non-metric pseudo-arc and counter examples to the Wood's conjecture

**Joint Continuum Theory and Set Theoretic Topology Seminar**

Sep 28, 2015 04:00 PM

Parker Hall 247 +/-1

Speaker: David Lipham

Title: 2^c different subcontinua of (C(H*) (where H* = βH - H) none of which are in H* (and where C(X) is the hyperspace of subcontinua of X.)

**Continuum Theory**

Sep 21, 2015 03:00 PM

Parker Hall 246

Dr. Baldwin will speak on "Homeomorphism Classes of Solenoids"

**Continuum Theory Seminar**

Sep 14, 2015 04:00 PM

Parker Hall 246(?)

Speaker: **Steven Clontz** ('15), University of North Carolina at Charlotte

Steven will talk about a couple of topological games he has been considering.

Abstract: A Corson compact space is a compact space which may be embedded in a Sigma-product of real lines; a Sigma-product of real lines is the collection of sequences in \(\mathbb R^\kappa\) for some cardinal \(\kappa\) for which all but countably many coordinates are zero. In particular, compact metrizable spaces are Corson compact. Clontz will speak about a joint result with Scott Varagona (University of Montevallo) showing that any generalized inverse limit of length \(\kappa\) obtained with a non-trivial idempotent continuum-valued u.s.c. bonding map is not Corson compact.

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Last Updated: 09/11/2015