Results 31 to 40 of about 1,769,588 (220)

Interlacing inequalities for totally nonnegative matrices [PDF]

, 2002
Suppose λ1⩾⋯⩾λn⩾0 are the eigenvalues of an n×n totally nonnegative matrix, and λ̃1⩾⋯⩾λ̃k are the eigenvalues of a k×k principal submatrix. A short proof is given of the interlacing inequalities:λi⩾λ̃i⩾λi+n−k,i=1,…,k.It is shown that if k=1,2,n−2,n−1, λi
Li, Chi-Kwong, Li, CK, Chi-Kwong Li, Mathias, Roy, Roy Mathias   +4 more
core   +1 more source

Front Propagation Through a Perforated Wall

Communications on Pure and Applied Mathematics, EarlyView.
ABSTRACT We consider a bistable reaction– diffusion equation ut=Δu+f(u)$u_t=\Delta u +f(u)$ on RN${\mathbb {R}}^N$ in the presence of an obstacle K$K$, which is a wall of infinite span with many holes. More precisely, K$K$ is a closed subset of RN${\mathbb {R}}^N$ with smooth boundary such that its projection onto the x1$x_1$‐axis is bounded and that ...
Henri Berestycki, François Hamel, Hiroshi Matano   +2 more
wiley   +1 more source

Compact Manifolds With Unbounded Nilpotent Fundamental Groups and Positive Ricci Curvature

Communications on Pure and Applied Mathematics, EarlyView.
ABSTRACT It follows from the work of Kapovitch and Wilking that a closed manifold with nonnegative Ricci curvature has a uniformly almost nilpotent fundamental group. Leftover questions and conjectures, have asked if in this context the fundamental group is actually uniformly almost abelian. The main goal of this work is to construct examples (Mk9,gk)$(
Elia Bruè, Aaron Naber, Daniele Semola
wiley   +1 more source

Theorems on Positive Data: On the Uniqueness of NMF [PDF]

, 2008
We investigate the conditions for which nonnegative matrix factorization (NMF) is unique and introduce several theorems which can determine whether the decomposition is in fact unique or not.
Pumbley, Mark, Plumbley, MD, Christensen, Mads Græsbøll; id_orcid, Hansen, LK, Lauerberg, Hans, Christensen, MG, Plumbley, Mark D., Jensen, Søren Holdt, Jensen, SH, Laurberg, Hans, Christensen, Mads Græsbøll, Hansen, Lars Kai, Laurberg, H   +12 more
core   +1 more source

Totally Nonnegative Tropical Flags and the Totally Nonnegative Flag Dressian [PDF]

, 2023
We study the totally nonnegative part of the complete flag variety and of its tropicalization. We show that Lusztig's notion of nonnegative complete flag variety coincides with the flags in the complete flag variety which have nonnegative Pl{\"u}cker ...
Boretsky, Jonathan
core   +1 more source

Exchange Rates and Sovereign Risk: A Nonlinear Approach Based on Local Gaussian Correlations

International Journal of Finance &Economics, EarlyView.
ABSTRACT We empirically assess the interlinkages between sovereign risk, measured in terms of CDS spreads, and exchange rates for a sample of emerging markets. Our period of analysis includes episodes of severe stress, such as the Global Financial Crisis, the COVID‐19 pandemic, and the Ukrainian War.
Reinhold Heinlein, Gabriella D. Legrenzi, Scott M. R. Mahadeo   +2 more
wiley   +1 more source

NIMFA: A Python Library for Nonnegative Matrix Factorization [PDF]

, 2012
NIMFA is an open-source Python library that provides a unified interface to nonnegative matrix factorization algorithms. It includes implementations of state-of-the-art factorization methods, initialization approaches, and quality scoring.
Zupan, Blaz, Zitnik, Marinka
core   +1 more source

Multiobjective Simulation–Optimization of Crop Allocation and Water Resources in Canal Command Areas Using Genetic Algorithms

Irrigation and Drainage, EarlyView.
ABSTRACT This study develops an integrated simulation–optimization framework for sustainable crop allocation and water resource management in the Bargarh Canal Command (BCC), eastern India. Efficient irrigation allocation remains a critical challenge due to competing demands, groundwater–surface water interactions and environmental constraints ...
Priyanka Mohapatra, J. C. Paul, Sushree Sangita Dash   +2 more
wiley   +1 more source

Two Two‐Tier Stochastic Frontier Replications

Journal of Applied Econometrics, EarlyView.
ABSTRACT We replicate the two foundational studies which proposed the two‐tier stochastic frontier model, first in the cross‐sectional setting and then for the fixed effects panel data model. We explore matters of software then and now, different mathematical formulations of the likelihood, and alternative current software tools.
Alecos Papadopoulos, Christopher Parmeter   +1 more
wiley   +1 more source

Jordan Structures of Totally Nonnegative Matrices

, 2005
An n × n matrix is said to be totally nonnegative if every minor of A is nonnegative. In this paper we completely characterize all possible Jordan canonical forms of irreducible totally nonnegative matrices.
Shaun M. Fallat, Michael I. Gekhtman
core   +1 more source