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In earlier papers, we showed a decomposition of the arcs of 2-diregular digraphs (2-dds) and used it to prove some conditions for these graphs to be non-Hamiltonian; we then extended this decomposition to a larger class of digraphs and used…

Combinatorics · Mathematics 2026-01-27 Munagala V. Ramanath

Necessary and sufficient conditions for the existence of a composite-system statistical operator, and, separately, for the possibility of its being correlated or uncorrelated, are derived in terms of its range dimension and the range…

Quantum Physics · Physics 2009-11-10 F. Herbut

Let Delta_{n-1} denote the (n-1)-dimensional simplex. Let Y be a random k-dimensional subcomplex of Delta_{n-1} obtained by starting with the full (k-1)-dimensional skeleton of Delta_{n-1} and then adding each k-simplex independently with…

Combinatorics · Mathematics 2007-05-23 R. Meshulam , N. Wallach

Classical complexity theory measures the cost of computing a function, but many computational tasks require committing to one valid output among several. We introduce determination depth -- the minimum number of sequential layers of…

Computational Complexity · Computer Science 2026-04-08 Joseph M. Hellerstein

The $2$-layer drawing model is a well-established paradigm to visualize bipartite graphs. Several beyond-planar graph classes have been studied under this model. Surprisingly, however, the fundamental class of $k$-planar graphs has been…

Discrete Mathematics · Computer Science 2020-08-24 Patrizio Angelini , Giordano Da Lozzo , Henry Förster , Thomas Schneck

A theory of rank $k\ge 2$ perturbation of symplectic matrices and Hamiltonian systems with periodic coefficients using a base of isotropic subspaces, is presented. After showing that the fundamental matrix ${\displaystyle…

Numerical Analysis · Mathematics 2017-12-12 Traoré G. Y. Arouna , Mouhamadou Dosso , Jean-Claude Koua Brou

We revisit Pollard's classical result on consistency for $k$-means clustering in Euclidean space, with a focus on extensions in two directions: first, to problems where the data may come from interesting geometric settings (e.g., Riemannian…

Statistics Theory · Mathematics 2025-07-01 Adam Quinn Jaffe

We obtain an exact necessary and sufficient condition for the existence and uniqueness of equilibrium asset prices in infinite horizon, discrete-time, arbitrage free environments. Through several applications we show how the condition…

General Finance · Quantitative Finance 2021-03-01 Jaroslav Borovicka , John Stachurski

Although effective for two dimensional (2D) systems, some approximations may fail in describing the properties of one-dimensional (1D) models, which belong to a different universality class. In this paper, we analyze the adequacy of the…

Strongly Correlated Electrons · Physics 2007-05-23 Adolfo Avella , Ferdinando Mancini , Maria del Mar Sanchez-Lopez

The structure of cones of positive and k-positive maps acting on a finite-dimensional Hilbert space is investigated. Special emphasis is given to their duality relations to the sets of superpositive and k-superpositive maps. We characterize…

Quantum Physics · Physics 2015-05-13 Lukasz Skowronek , Erling Stormer , Karol Zyczkowski

Recent spectral clustering methods are a propular and powerful technique for data clustering. These methods need to solve the eigenproblem whose computational complexity is $O(n^3)$, where $n$ is the number of data samples. In this paper, a…

Machine Learning · Computer Science 2007-11-26 Chunjing Xu , Jianzhuang Liu , Xiaoou Tang

In this work, we first revise some extensions of the standard Hopfield model in the low storage limit, namely the correlated attractor case and the multitasking case recently introduced by the authors. The former case is based on a…

Disordered Systems and Neural Networks · Physics 2012-05-23 Elena Agliari , Adriano Barra , Andrea De Antoni , Andrea Galluzzi

Given an undirected graph, are there $k$ matchings whose union covers all of its nodes, that is, a matching-$k$-cover? A first, easy polynomial solution from matroid union is possible, as already observed by Wang, Song and Yuan…

Combinatorics · Mathematics 2021-02-05 Dehia Ait Ferhat , Zoltán Király , András Sebő , Gautier Stauffer

Boundary conditions compatible with integrability are obtained for two dimensional models by solving the factorizability equations for the reflection matrices $K^{\pm}(\theta)$. For the six vertex model the general solution depending on…

High Energy Physics - Theory · Physics 2009-10-22 H. J. de Vega , A. González Ruiz

In this thesis, I study the local charges $\{Q_k\}$ in the one-dimensional Hubbard model, which is an integrable system used for theoretical studies of non-perturbative effects in strongly correlated electron systems. I obtained their…

Statistical Mechanics · Physics 2024-02-15 Kohei Fukai

Mixed states that are uniquely determined among all (UDA) states are vital in efficient quantum tomography. We show the necessary and sufficient conditions by which some multipartite mixed states are UDA by their $k$-partite reduced density…

Quantum Physics · Physics 2026-01-22 Xinyu Qiu , Lin Chen , Genwei Li , Delin Chu

We investigate the asymptotic behavior of probability measures associated with stochastic dynamical systems featuring either globally contracting or $B_{r}$-contracting drift terms. While classical results often assume constant diffusion…

Dynamical Systems · Mathematics 2025-05-14 Simone Betteti , Francesco Bullo

Hopfield networks are a variant of associative memory that recall information stored in the couplings of an Ising model. Stored memories are fixed points for the network dynamics that correspond to energetic minima of the spin state. We…

Quantum Physics · Physics 2014-12-15 Hadayat Seddiqi , Travis S. Humble

Let $K \subset {\mathbb R}^n$ be a compact definable set in an o-minimal structure over $\mathbb R$, e.g., a semi-algebraic or a subanalytic set. A definable family $\{ S_\delta|\> 0< \delta \in {\mathbb R} \}$ of compact subsets of $K$, is…

Algebraic Geometry · Mathematics 2017-05-17 Saugata Basu , Andrei Gabrielov , Nicolai Vorobjov

We derive the necessary and sufficient condition, for a given Polynomial Recurrence Sequence to converge to a given target rational K. By converge, we mean that the Nth term of the sequence, is equal to K, as N tends to positive infinity.…

Discrete Mathematics · Computer Science 2013-07-09 Deepak Ponvel Chermakani