Results 91 to 100 of about 68,778 (203)
On 3‐Designs From P G L ( 2 , q )
Journal of Combinatorial Designs, Volume 33, Issue 11, Page 428-432, November 2025.ABSTRACT The group P G L ( 2 , q ) acts 3‐transitively on the projective line G F ( q ) ∪ { ∞ }. Thus, an orbit of its action on the k‐subsets of the projective line is the block set of a 3‐ ( q + 1 , k , λ ) design. We find the parameters of the designs formed by the orbit of a block of the form 〈 θ r 〉 or 〈 θ r 〉 ∪ { 0 }, where θ is a primitive ...
Paul Tricot
wiley +1 more source
Chordal Graphs, Even‐Hole‐Free Graphs and Sparse Obstructions to Bounded Treewidth
Journal of Graph Theory, Volume 110, Issue 3, Page 351-365, November 2025.ABSTRACT Even‐hole‐free graphs pose a central challenge in identifying hereditary classes of bounded treewidth. We investigate this matter by presenting and studying the following conjecture: for an integer t ≥ 4 and a graph H, every even‐hole‐free graph of large enough treewidth has an induced subgraph isomorphic to either K t or H, if (and only if) H
Sepehr Hajebi
wiley +1 more source
Journal of Combinatorial Designs, Volume 33, Issue 10, Page 379-387, October 2025.ABSTRACT The E ( s 2 )‐optimal and minimax‐optimal supersaturated designs (SSDs) with 12 rows, 11 q columns, and s max = 4 are enumerated in a computer search: there are, respectively, 34, 146, 0, 3, and 1 such designs for q = 2 , 3 , 4 , 5, and 6. Cheng and Tang proved that for q > 6, there are no such SSDs.
Luis B. Morales
wiley +1 more source
Symmetric 2‐ ( 35 , 17 , 8 ) Designs With an Automorphism of Order 2
Journal of Combinatorial Designs, Volume 33, Issue 10, Page 399-403, October 2025.ABSTRACT The largest prime p that can be the order of an automorphism of a 2‐ ( 35 , 17 , 8 ) design is p = 17, and all 2‐ ( 35 , 17 , 8 ) designs with an automorphism of order 17 were classified by Tonchev. The symmetric 2‐ ( 35 , 17 , 8 ) designs with automorphisms of an odd prime order p < 17 were classified in Bouyukliev, Fack and Winne and ...
Sanja Rukavina, Vladimir D. Tonchev
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Abundant Neighborhoods, Two‐Sided Markets, and Maximal Matchings
Naval Research Logistics (NRL), Volume 72, Issue 7, Page 1022-1035, October 2025.ABSTRACT I introduce a new graph‐theoretic property called abundant neighborhoods. This property is motivated by studying the thickness of economic markets. A vertex is, roughly, guaranteed to match if and only if it has an abundant neighborhood.
Muhammad Maaz
wiley +1 more source
Average‐Case Matrix Discrepancy: Satisfiability Bounds
Random Structures &Algorithms, Volume 67, Issue 3, October 2025.ABSTRACT Given a sequence of d×d$$ d\times d $$ symmetric matrices {Wi}i=1n$$ {\left\{{\mathbf{W}}_i\right\}}_{i=1}^n $$, and a margin Δ>0$$ \Delta >0 $$, we investigate whether it is possible to find signs (ε1,…,εn)∈{±1}n$$ \left({\varepsilon}_1,\dots, {\varepsilon}_n\right)\in {\left\{\pm 1\right\}}^n $$ such that the operator norm of the signed sum ...
Antoine Maillard
wiley +1 more source
Moments, sums of squares, and tropicalization
Journal of the London Mathematical Society, Volume 112, Issue 4, October 2025.Abstract We use tropicalization to study the duals to cones of nonnegative polynomials and sums of squares on a semialgebraic set S$S$. The truncated cones of moments of measures supported on the set S$S$ are dual to nonnegative polynomials on S$S$, while “pseudomoments” are dual to sums of squares approximations to nonnegative polynomials.
Grigoriy Blekherman +4 more
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On extremal problems associated with random chords on a circle
Mathematika, Volume 71, Issue 4, October 2025.Abstract Inspired by the work of Karamata, we consider an extremization problem associated with the probability of intersecting two random chords inside a circle of radius r,r∈(0,1]$r, \, r \in (0,1]$, where the endpoints of the chords are drawn according to a given probability distribution on S1$\mathbb {S}^1$.
Cynthia Bortolotto, João P. G. Ramos
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Integer colorings with forbidden rainbow sums
, 2020 For a set of positive integers $A \subseteq [n]$, an $r$-coloring of $A$ is rainbow sum-free if it contains no rainbow Schur triple. In this paper we initiate the study of the rainbow Erd\H{o}s-Rothchild problem in the context of sum-free sets, which ...
Cheng, Yangyang +4 more
core
A note on the magnetic Steklov operator on functions
Mathematika, Volume 71, Issue 4, October 2025.Abstract We consider the magnetic Steklov eigenvalue problem on compact Riemannian manifolds with boundary for generic magnetic potentials and establish various results concerning the spectrum. We provide equivalent characterizations of magnetic Steklov operators which are unitarily equivalent to the classical Steklov operator and study bounds for the ...
Tirumala Chakradhar +3 more
wiley +1 more source