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We study the class of pseudocompact C*-algebras, which are the logical limits of finite-dimensional C*-algebras. The pseudocompact C*-algebras are unital, stably finite, real rank zero, stable rank one, and tracial. We show that the…

Operator Algebras · Mathematics 2016-09-26 Stephen Hardy

In this paper, we construct a seven-term exact sequence involving the cohomology groups of a group extension. Although the existence of such a sequence can be derived using spectral sequence arguments, there is little knowledge about some…

Group Theory · Mathematics 2012-01-18 Karel Dekimpe , Manfred Hartl , Sarah Wauters

By a theorem due to Kato and Ohtake, any (not necessarily strict) Morita context induces an equivalence between appropriate subcategories of the module categories of the two rings in the Morita context. These are in fact categories of firm…

Rings and Algebras · Mathematics 2012-01-27 Gabriella Böhm , Joost Vercruysse

Strictly proper kernel scores are well-known tool in probabilistic forecasting, while characteristic kernels have been extensively investigated in the machine learning literature. We first show that both notions coincide, so that insights…

Functional Analysis · Mathematics 2017-12-15 Ingo Steinwart , Johanna F. Ziegel

Let $\mathscr{A}$ be an abelian category and $\mathscr{C}$ an additive full subcategory of $\mathscr{A}$. We provide a method to construct a proper $\mathscr{C}$-resolution (resp. coproper $\mathscr{C}$-coresolution) of one term in a short…

K-Theory and Homology · Mathematics 2012-03-20 Zhaoyong Huang

Continuous actions of topological groups on compact Hausdorff spaces $X$ are investigated which induce almost periodic functions in the corresponding commutative C*-algebra. The unique invariant mean on the group resulting from averaging…

Operator Algebras · Mathematics 2009-03-11 M. Frank , V. Manuilov , E. Troitsky

In this article, we generalize a previously defined set of axioms for a closure operation that induces balanced big Cohen-Macaulay modules. While the original axioms were only defined in terms of finitely generated modules, these new ones…

Commutative Algebra · Mathematics 2018-02-01 Geoffrey D. Dietz

Approximate morphisms have seen significant study across many areas of mathematics, for instance, in the theory of Absolute (Neighborhood) Retracts in topology, or of almost-commuting unitary matrices in analysis. This paper initiates study…

Operator Algebras · Mathematics 2026-01-14 Samantha Pilgrim

A deductive system is structurally complete if its admissible inference rules are derivable. For several important systems, like modal logic S5, failure of structural completeness is caused only by the underivability of passive rules, i.e.…

Logic · Mathematics 2014-08-26 Wojciech Dzik , Michal M. Stronkowski

We show that certain C*-algebras which have been studied among others by Arzumanian, Vershik, Deaconu, and Renault in connection to a measure preserving transformation of a measure space and/or to a covering map of a compact space are…

Operator Algebras · Mathematics 2007-05-23 R. Exel , A. Vershik

Weak-memory models are standard formal specifications of concurrency across hardware, programming languages, and distributed systems. A fundamental computational problem is consistency testing: is the observed execution of a concurrent…

Programming Languages · Computer Science 2023-11-16 Soham Chakraborty , Shankaranarayanan Krishna , Umang Mathur , Andreas Pavlogiannis

This monograph introduces a framework for genuine proper equivariant stable homotopy theory for Lie groups. The adjective `proper' alludes to the feature that equivalences are tested on compact subgroups, and that the objects are built from…

Algebraic Topology · Mathematics 2023-08-15 Dieter Degrijse , Markus Hausmann , Wolfgang Lück , Irakli Patchkoria , Stefan Schwede

A group may be considered $C^*$-stable if almost representations of the group in a $C^*$-algebra are always close to actual representations. We initiate a systematic study of which discrete groups are $C^*$-stable or only stable with…

Operator Algebras · Mathematics 2021-04-21 Søren Eilers , Tatiana Shulman , Adam P. W. Sørensen

A mapping $f: {\mathcal M} \to {\mathcal N}$ between Hilbert $C^*$-modules approximately preserves the inner product if \[\|< f(x), f(y)> - < x, y> \| \leq \phi(x, y),\] for an appropriate control function $\phi(x,y)$ and all $x, y \in…

Operator Algebras · Mathematics 2008-04-30 Jacek Chmielinski , Mohammad Sal Moslehian

Fourth-order accurate compact schemes for variable coefficient convection diffusion equations are considered. A sufficient condition for the stability of the fully discrete problem is derived using a difference equation based approach. The…

Numerical Analysis · Mathematics 2024-01-30 Anindya Goswami , Kuldip Singh Patel , Pradeep Kumar Sahu

We extend McCarthy's stabilization construction to exact $\infty$-categories. This is achieved by constructing, for any functor from exact $\infty$-categories to a fixed stable $\infty$-category $\mathcal{A}$, a coherent chain complex in…

Algebraic Topology · Mathematics 2025-01-29 Ettore Aldrovandi , Arash Karimi

Given a commutative ring $R$ and finitely generated ideal $I$, one can consider the classes of $I$-adically complete, $L_0^I$-complete and derived $I$-complete complexes. Under a mild assumption on the ideal $I$ called weak pro-regularity,…

Commutative Algebra · Mathematics 2025-05-29 Luca Pol , Jordan Williamson

We present necessary and sufficient optimality conditions for finite time optimal control problems for a class of hybrid systems described by linear complementarity models. Although these optimal control problems are difficult in general…

Optimization and Control · Mathematics 2016-10-11 Andreas B. Hempel , Paul Goulart , John Lygeros

Multiprocess systems, including grid systems, multiprocessors and multicore computers, incorporate a variety of specialized hardware and software mechanisms, which speed computation, but result in complex memory behavior. As a consequence,…

Distributed, Parallel, and Cluster Computing · Computer Science 2013-06-04 Steven Cheng , Lisa Higham , Jalal Kawash

Let $(C,\underline{w})$ be a polarized nodal reducible curve. In this paper we consider coherent systems of type $(r,d,k)$ on $C$ with $k < r$. We prove that the moduli spaces of $(\underline{w},\alpha)$-stable coherent systems stabilize…

Algebraic Geometry · Mathematics 2022-02-10 Sonia Brivio , Filippo F. Favale