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We survey two decades of work on the (sequential) topological complexity of configuration spaces of graphs (ordered and unordered), aiming to give an account that is unifying, elementary, and self-contained. We discuss the traditional…

Algebraic Topology · Mathematics 2024-06-27 Ben Knudsen

We consider commutative C* -algebras of Toeplitz operators in the weighted Bergman space on the unit ball in $\mathbb{C}^{\mathbf{n}}$. For the algebras of elliptic type we find a new representation, namely as the algebra of operators which…

Functional Analysis · Mathematics 2022-11-22 Grigori Rozenblum , Nikolai Vasilevski

Using basic topology and linear algebra, we define a plethora of invariants of boundary links whose values are power series with noncommuting variables. These turn out to be useful and elementary reformulations of an invariant originally…

Geometric Topology · Mathematics 2007-05-23 Stavros Garoufalidis , Jerome Levine

The higher topological complexity of a space $X$, $\text{TC}_r(X)$, $r=2,3,\ldots$, and the topological complexity of a map $f$, $\text{TC}(f)$, have been introduced by Rudyak and Pave\v{s}i\'{c}, respectively, as natural extensions of…

Algebraic Topology · Mathematics 2023-03-24 Cesar A. Ipanaque Zapata , Jesús González

We present a new approach to equivariant version of the topological complexity, called a symmetric topological complexity. It seems that the presented approach is more adequate for the analysis of an impact of symmetry on the the motion…

Algebraic Topology · Mathematics 2015-06-12 Wojciech Lubawski , Wacław Marzantowicz

Non-commutative multivariable versions of weighted shift operators arise naturally as `weighted' left creation operators acting on the Fock space Hilbert space. We identify a natural notion of periodicity for these $N$-tuples, and then find…

Operator Algebras · Mathematics 2007-05-23 David W. Kribs

Gelfand - Na\u{i}mark theorem supplies contravariant functor from a category of commutative $C^*-$ algebras to a category of locally compact Hausdorff spaces. Therefore any commutative $C^*-$ algebra is an alternative representation of a…

Operator Algebras · Mathematics 2014-01-28 Petr R. Ivankov

Locally noncommutative spacetimes provide a refined notion of noncommutative spacetimes where the noncommutativity is present only for small distances. Here we discuss a non-perturbative approach based on Rieffel's strict deformation…

Quantum Algebra · Mathematics 2009-11-11 Jakob G. Heller , Nikolai Neumaier , Stefan Waldmann

For any topological space there is a sheaf cohomology. A Grothendieck topology is a generalization of the classical topology such that it also possesses a sheaf cohomology. On the other hand any noncommutative $C^*$-algebra is a…

Operator Algebras · Mathematics 2024-04-01 Petr R. Ivankov

We develop the properties of the $n$-th sequential topological complexity $TC_n$, a homotopy invariant introduced by the third author as an extension of Farber's topological model for studying the complexity of motion planning algorithms in…

Algebraic Topology · Mathematics 2014-11-11 Ibai Basabe , Jesus Gonzalez , Yuli B. Rudyak , Dai Tamaki

Any $C^*$-algebra can be regarded as a generalization of locally compact, Hausdorff topological space $\mathcal X$. From the commutative commutative Gelfand-Na\u{\i}mark theorem it follows that the spectrum of any commutative $C^*$-algebra…

Operator Algebras · Mathematics 2026-03-17 Petr Ivankov

Starting with a $W^{*}$-algebra $M$ we use the inverse system obtained by cutting down $M$ by its (central) projections to define an inverse limit of $W^{*}$-algebras, and show that how this pro-$W^{*}$-algebra encodes the local structure…

Operator Algebras · Mathematics 2007-05-23 Massoud Amini

We carefully define and study C*-algebras over topological spaces, possibly non-Hausdorff, and review some relevant results from point-set topology along the way. We explain the triangulated category structure on the bivariant Kasparov…

K-Theory and Homology · Mathematics 2015-10-23 Ralf Meyer , Ryszard Nest

We use compactifications of C*-algebras to introduce noncommutative coarse geometry. We transfer a noncommutative coarse structure on a C*-algebra with an action of a locally compact Abelian group by translations to Rieffel deformations and…

Operator Algebras · Mathematics 2016-10-28 Tathagata Banerjee , Ralf Meyer

Gelfand - Na\u{i}mark theorem supplies a one to one correspondence between commutative $C^*$-algebras and locally compact Hausdorff spaces. So any noncommutative $C^*$-algebra can be regarded as a generalization of a topological space.…

Operator Algebras · Mathematics 2014-11-11 Petr R. Ivankov

We introduce a classification of locally compact Hausdorff topological spaces with respect to the behavior of $\sigma$-compact subsets, and relying on this classification we study properties of corresponding $C^*$-algebras in terms of frame…

Operator Algebras · Mathematics 2022-06-22 Denis Fufaev

We investigate the $\mathcal F$-Borel complexity of topological spaces in their different compactifcations. We provide a simple proof of the fact that a space can have arbitrarily many different complexities in different compactifications.…

General Topology · Mathematics 2018-04-24 Vojtěch Kovařík

We prove the existence of commutative $C^*$-algebras of Toeplitz operators on every weighted Bergman space over the complex projective space $\mathbb{P}^n(\mathbb{C})$. The symbols that define our algebras are those that depend only on the…

Operator Algebras · Mathematics 2012-01-11 Raul Quiroga-Barranco , A. Sanchez-Nungaray

Lattice discretizations of continuous manifolds are common tools used in a variety of physical contexts. Conventional discrete approximations, however, cannot capture all aspects of the original manifold, notably its topology. In this paper…

High Energy Physics - Theory · Physics 2009-10-28 A. P. Balachandran , G. Bimonte , E. Ercolessi , G. Landi , F. Lizzi , G. Sparano , P. Teotonio-Sobrinho

The complexity of algorithms solving the motion planning problem is measured by a homotopy invariant TC(X) of the configuration space X of the system. Previously known lower bounds for TC(X) use the structure of the cohomology algebra of X.…

Algebraic Topology · Mathematics 2007-07-07 Michael Farber , Mark Grant