P. Choudhury

activity

20182026

most citedSign non-reversal property for totally non-negative and totally positive matrices, and testing total positivity of their interval hull

7 citations · 17 across the 21 of their papers we have counts for

collaborators

24 papers

math.CO2026

Uniform Intersection Numbers and Subgroup-Based Generating Graphs of Groups

Projesh Nath Choudhury, Biswaranjan Khanra

The uniform intersection number of a finite group $G$ , denoted by $u i (G)$ , is the smallest positive integer $k$ such that the intersection of any $k$ distinct maximal subgroups of…

math.RA2026

SNT-Rank: Kronecker Products and Euclidean Distance Matrices

Bharat Pratap Chauhan, Projesh Nath Choudhury

Symmetric nonnegative matrix trifactorizations (SN-Trifactorizations) were introduced by Bukovšek-Šmigoc [Linear Algebra Appl. 2023] as a symmetric analogue of nonnegative matrix f…

math.FA2026

Linear preserver problems in matrix positivity theory

Projesh Nath Choudhury, Shivangi Yadav

Linear preserver problems have been a central focus of research in matrix theory and operator theory for more than a century, beginning with Frobenius' 1897 characterization of det…

math.RA2026

Semigroup automorphisms of total positivity

Projesh Nath Choudhury, Shaun Fallat, Chi-Kwong Li

Totally positive (TP) and totally nonnegative (TN) matrices connect to analysis, mechanics, and to dual canonical bases in reductive groups, by well-known works of Schoenberg, Gant…

math.FA2025

Entrywise preservers of sign regularity

Projesh Nath Choudhury, Shivangi Yadav

Entrywise functions preserving positivity and related notions have a rich history, beginning with the seminal works of Schur, Pólya-Szegő, Schoenberg, and Rudin. Following their cl…

math.CO2025

Quadratic Embedding Constants of Cartesian Products and Joins of Graphs

Projesh Nath Choudhury, Raju Nandi

The quadratic embedding constant (QEC) of a finite, simple, connected graph originated from the classical work of Schoenberg [Ann. of Math., 1935] and [Trans. Amer. Math. Soc., 193…

math.RA2025

Positivity of GCD tensors and their determinants

Projesh Nath Choudhury, Krushnachandra Panigrahy

Let $S = {s_{1}, s_{2}, \dots, s_{n}}$ be an ordered set of $n$ distinct positive integers. The $m$ th-order $n$ -dimensional tensor $T_{[S]} = (t_{i_{1} i_{2} \dots i_{m}}),$ where $t_{i…

math.RA2024

Constructing strictly sign regular matrices of all sizes and sign patterns

Projesh Nath Choudhury, Shivangi Yadav

The class of strictly sign regular (SSR) matrices has been extensively studied by many authors over the past century, notably by Schoenberg, Motzkin, Gantmacher, and Krein. A class…

math.FA2024

Sign regularity preserving linear operators

Projesh Nath Choudhury, Shivangi Yadav

A matrix $A \in R^{m \times n}$ is strictly sign regular/SSR (or sign regular/SR) if for each $1 \leq k \leq min {m, n}$ , all (non-zero) $k \times k$ minors of $A$ have the…

math.CO2023

The additive-multiplicative distance matrix of a graph, and a novel third invariant

Projesh Nath Choudhury, Apoorva Khare

Graham showed with Pollak and Hoffman-Hosoya that for any directed graph $G$ with strong blocks $G_{e}$ , the determinant $det (D_{G})$ and cofactor-sum $co f (D_{G})$ of the distance matri…

math.RA2023

Sign regular matrices and variation diminution: single-vector tests and characterizations, following Schoenberg, Gantmacher-Krein, and Motzkin

Projesh Nath Choudhury, Shivangi Yadav

Variation diminution (VD) is a fundamental property in total positivity theory, first studied in 1912 by Fekete-Pólya for one-sided Pólya frequency sequences, followed by Schoenber…

math.CO2023

Quadratic embedding constants of graphs: Bounds and distance spectra

Projesh Nath Choudhury, Raju Nandi

The quadratic embedding constant (QEC) of a finite, simple, connected graph $G$ is the maximum of the quadratic form of the distance matrix of $G$ on the subset of the unit sphere…

math.CO2022

Blowup polynomials and delta-matroids of graphs

Projesh Nath Choudhury, Apoorva Khare

For every finite simple connected graph $G = (V, E)$ , we introduce an invariant, its blowup-polynomial $p_{G} ({n_{v} : v \in V})$ . This is obtained by dividing the determinant of th…

math.RA2021

Nesbitt and Shapiro Cyclic Sum Inequalities for Positive Definite Matrices

Projesh Nath Choudhury, K. C. Sivakumar

The aim of this note is to show that certain number theoretic inequalities due to Nesbitt and Shapiro have noncommutative counterparts involving positive definite matrices.

math.CO2021

Multivariate blowup-polynomials of graphs

Projesh Nath Choudhury, Apoorva Khare

In recent joint work (2021), we introduced a novel multivariate polynomial attached to every metric space - in particular, to every finite simple connected graph $G$ - and showed i…

math.MG2021★ 1 cited

The blowup-polynomial of a metric space: connections to stable polynomials, graphs and their distance spectra

Projesh Nath Choudhury, Apoorva Khare

To every finite metric space $X$ , including all connected unweighted graphs with the minimum edge-distance metric, we attach an invariant that we call its blowup-polynomial $p_X(\{…

math.RA2021★ 3 cited

Total negativity: Characterizations and single-vector tests

Projesh Nath Choudhury

A matrix is called totally negative (totally non-positive) of order $k$ , if all its minors of size at most $k$ are negative (non-positive). The objective of this article is to prov…

math.RA2021

Characterizing total positivity: single vector tests via Linear Complementarity, sign non-reversal, and variation diminution

Projesh Nath Choudhury

A matrix $A$ is called totally positive (or totally non-negative) of order $k$ , denoted by TP_k (or TN_k), if all minors of size at most $k$ are positive (or non-negative). These m…

math.RA2020

Interval hulls of $N$ -matrices and almost $P$ -matrices

Projesh Nath Choudhury, M. Rajesh Kannan

We establish a characterization of almost $P$ -matrices via a sign non-reversal property. In this we are inspired by the analogous results for $N$ -matrices. Next, the interval hull…

math.RA2020★ 7 cited

Sign non-reversal property for totally non-negative and totally positive matrices, and testing total positivity of their interval hull

Projesh Nath Choudhury, M. Rajesh Kannan, Apoorva Khare

A matrix $A$ is totally positive (or non-negative) of order $k$ , denoted $T P_{k}$ (or $T N_{k}$ ), if all minors of size $\leq k$ are positive (or non-negative). It is well-known that su…

math.FA2020

Bounds for a solution set of linear complementarity problems over Hilbert spaces

Projesh Nath Choudhury, M. Rajesh Kannan, K. C. Sivakumar

Let $H$ be a real Hilbert space. In this short note, using some of the properties of bounded linear operators with closed range defined on $H$ , certain bounds for a specific convex…

math.RA2020

How to Detect and Construct N-matrices

Projesh Nath Choudhury, Michael J. Tsatsomeros

N-matrices are real $n \times n$ matrices all of whose principal minors are negative. We provide (i) an $O (2^{n})$ test to detect whether or not a given matrix is an N-matrix, and (ii…

math.CO2019★ 6 cited

Distance matrices of a tree: two more invariants, and in a unified framework

Projesh Nath Choudhury, Apoorva Khare

Graham-Pollak showed that for $D = D_{T}$ the distance matrix of a tree $T$ , det $(D)$ depends only on its number of edges. Several other variants of $D$ , including directed/multiplic…

math.FA2018

A note on linear preservers on semipositive and minimal semipositive matrices

Projesh Nath Choudhury, M. Rajesh Kannan, K. C. Sivakumar

Semipositive matrices (matrices that map at least one nonnegative vector to a positive vector) and minimally semipositive matrices (semipositive matrices whose no column-deleted su…

Uniform Intersection Numbers and Subgroup-Based Generating Graphs of Groups

SNT-Rank: Kronecker Products and Euclidean Distance Matrices

Linear preserver problems in matrix positivity theory

Semigroup automorphisms of total positivity

Entrywise preservers of sign regularity

Quadratic Embedding Constants of Cartesian Products and Joins of Graphs

Positivity of GCD tensors and their determinants

Constructing strictly sign regular matrices of all sizes and sign patterns

Sign regularity preserving linear operators

The additive-multiplicative distance matrix of a graph, and a novel third invariant

Sign regular matrices and variation diminution: single-vector tests and characterizations, following Schoenberg, Gantmacher-Krein, and Motzkin

Quadratic embedding constants of graphs: Bounds and distance spectra

Blowup polynomials and delta-matroids of graphs

Nesbitt and Shapiro Cyclic Sum Inequalities for Positive Definite Matrices

Multivariate blowup-polynomials of graphs

The blowup-polynomial of a metric space: connections to stable polynomials, graphs and their distance spectra

Total negativity: Characterizations and single-vector tests

Characterizing total positivity: single vector tests via Linear Complementarity, sign non-reversal, and variation diminution

Interval hulls of N-matrices and almost P-matrices

Sign non-reversal property for totally non-negative and totally positive matrices, and testing total positivity of their interval hull

Bounds for a solution set of linear complementarity problems over Hilbert spaces

How to Detect and Construct N-matrices

Distance matrices of a tree: two more invariants, and in a unified framework

A note on linear preservers on semipositive and minimal semipositive matrices

Interval hulls of $N$ -matrices and almost $P$ -matrices