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We show that Connes' embedding conjecture on von Neumann algebras is equivalent to the existence of certain algebraic certificates for a polynomial in noncommuting variables to satisfy the following nonnegativity condition: The trace is…

Operator Algebras · Mathematics 2011-04-19 Igor Klep , Markus Schweighofer

The existence of closed trapped surfaces need not imply a cosmological singularity when the spatial hypersurfaces are compact. This is illustrated by a variety of examples, in particular de Sitter spacetime admits many closed trapped…

General Relativity and Quantum Cosmology · Physics 2015-06-25 George F R Ellis

We investigate the parameterized complexity of generalisations and variations of the dominating set problem on classes of graphs that are nowhere dense. In particular, we show that the distance-d dominating-set problem, also known as the…

Data Structures and Algorithms · Computer Science 2009-07-27 Anuj Dawar , Stephan Kreutzer

We discuss dense embeddings of surface groups and fully residually free groups in topological groups. We show that a compact topological group contains a nonabelian dense free group of finite rank if and only if it contains a dense surface…

Group Theory · Mathematics 2009-03-02 Emmanuel Breuillard , Tsachik Gelander , Juan Souto , Peter Storm

We prove a generic flatness result for the cohomology of thickenings of a projective scheme that is smooth over a Noetherian domain containing a field of characteristic zero. Our study is motivated, in part, by a classical question in…

Algebraic Geometry · Mathematics 2026-03-06 Edoardo Ballico , Yairon Cid-Ruiz , Anurag K. Singh

A compact topological space X is spectral if it is sober (i.e., every irreducible closed set is the closure of a unique singleton) and the compact open subsets of X form a basis of the topology of X, closed under finite intersections.…

Rings and Algebras · Mathematics 2017-12-01 Friedrich Wehrung

We provide a simple proof that graphs in a general class of self-similar networks have zero percolation threshold. The considered self-similar networks include random scale-free graphs with given expected node degrees and zero clustering,…

Disordered Systems and Neural Networks · Physics 2011-01-28 M. Angeles Serrano , Dmitri Krioukov , Marian Boguna

We prove that any weakly non-collapsed RCD space is actually non-collapsed, up to a renormalization of the measure. This confirms a conjecture raised by De Philippis and the second named author in full generality. One of the auxiliary…

Differential Geometry · Mathematics 2022-10-11 Camillo Brena , Nicola Gigli , Shouhei Honda , Xingyu Zhu

The aim of this paper is introduce and initiate the study of extremally $T_1$-spaces, i.e., the spaces where all hereditarily compact $C_2$-subspaces are closed. A $C_2$-space is a space whose nowhere dense sets are finite.

General Topology · Mathematics 2007-05-23 Julian Dontchev , Maximilian Ganster , Laszlo Zsilinszky

In this paper, we prove the following Theorems 1. An extremally disconnected space $X$ has the semi-Menger property if and only if One does not have a winning strategy in the game $G_{fin}(sO,sO)$. 2. An extremally disconnected space $X$…

General Topology · Mathematics 2023-03-10 Manoj Bhardwaj , Alexander V. Osipov

Hardy space on the polydisk provides the setting for a global description of scattering in piecewise-constant layered media, giving a simple qualitative interpretation for the nonlinear dependence of the Green's function on reflection…

Mathematical Physics · Physics 2013-06-13 Peter C. Gibson

Answering a question raised by V. V. Tkachuk, we present several examples of $\sigma$-compact spaces, some only consistent and some in ZFC, that are not countably tight but in which the closure of any discrete subset is countably tight. In…

General Topology · Mathematics 2024-11-08 István Juhász , Jan van Mill

Given a complete non-compact surface embedded in R^3, we consider the Dirichlet Laplacian in a layer of constant width about the surface. Using an intrinsic approach to the layer geometry, we generalise the spectral results of an original…

Mathematical Physics · Physics 2015-06-26 G. Carron , P. Exner , D. Krejcirik

We provide an alternative view of some results in [1, 3, 11]. In particular, we prove that (1) if a continuous self-map of a compact metric space has the shadowing, then the union of the basins of terminal chain components is a dense…

Dynamical Systems · Mathematics 2025-02-19 Noriaki Kawaguchi

This note concerns the topology of the connected components of the zero sets of monochromatic random waves on compact Riemannian manifolds without boundary. In [SW] it is shown that these are distributed according to a universal measure on…

Mathematical Physics · Physics 2014-12-16 Yaiza Canzani , Peter Sarnak

Non-Hermitian systems have been discussed mostly in the context of open systems and nonequilibrium. Recent experimental progress is much from optical, cold-atomic, and classical platforms due to the vast tunability and clear identification…

Mesoscale and Nanoscale Physics · Physics 2024-01-25 Xiao-Xiao Zhang , Naoto Nagaosa

We construct a consistent example of a topological space $Y=X \cup \{\infty\}$ such that: 1) $Y$ is regular. 2) Every $G_\delta$ subset of $Y$ is open. 3) The point $\infty$ is not isolated, but it is not in the closure of any discrete…

General Topology · Mathematics 2024-03-05 Santi Spadaro , Paul Szeptycki

We prove that there are no minimal hypersurfaces properly immersed in any region of the Euclidean space bounded by unstable minimal cones. We also prove the analogous result for $r$-minimal hypersurfaces.

Differential Geometry · Mathematics 2019-06-19 Marcos Petrúcio Cavalcante , Wagner Oliveira Costa-Filho

In the present paper, we give a simple proof of the level density of fixed trace square ensemble.We derive the integral equation of the level density of fixed trace square ensemble.Then we analyze the asymptotic behavior of the level…

Mathematical Physics · Physics 2008-04-16 Da Xu , Lihe Wang

We define the scattered subsets of a group as asymptotic counterparts of scattered subspaces of a topological space, and prove that a subset $A$ of a group $G$ is scattered if and only if $A$ contains no piecewise shifted $IP$-subsets. For…

Group Theory · Mathematics 2013-12-30 T. O. Banakh , I. V. Protasov , S. V. Slobodianiuk