Results 71 to 80 of about 99,508 (238)

International Journal of Mathematical Combinatorics, vol. 2 / 2018

open access: yes, 2018
The International J.Mathematical Combinatorics (ISSN 1937-1055) is a fully refereed international journal, sponsored by the MADIS of Chinese Academy of Sciences and published in USA quarterly comprising 110-160 pages approx. per volume, which publishes original research papers and survey articles in all aspects of Smarandache multi-spaces, Smarandache ...
openaire   +1 more source

Real models for the framed little n$n$‐disks operads

open access: yesJournal of Topology, Volume 18, Issue 4, December 2025.
Abstract We study the action of the orthogonal group on the little n$n$‐disks operads. As an application we provide small models (over the reals) for the framed little n$n$‐disks operads. It follows in particular that the framed little n$n$‐disks operads are formal (over the reals) for n$n$ even and coformal for all n$n$.
Anton Khoroshkin, Thomas Willwacher
wiley   +1 more source

Commuting Pairs in Quasigroups

open access: yesJournal of Combinatorial Designs, Volume 33, Issue 11, Page 418-427, November 2025.
ABSTRACT A quasigroup is a pair ( Q , ∗ ), where Q is a nonempty set and ∗ is a binary operation on Q such that for every ( a , b ) ∈ Q 2, there exists a unique ( x , y ) ∈ Q 2 such that a ∗ x = b = y ∗ a. Let ( Q , ∗ ) be a quasigroup. A pair ( x , y ) ∈ Q 2 is a commuting pair of ( Q , ∗ ) if x ∗ y = y ∗ x.
Jack Allsop, Ian M. Wanless
wiley   +1 more source

On 3‐Designs From P G L ( 2 , q )

open access: yesJournal 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

open access: yesJournal 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

Mathematical Combinatorics & Smarandache Multi-Spaces (New Expanded Edition) [PDF]

open access: yes, 2013
This book is for young students, words of one mathematician, also being a physicist and an engineer to young students. By recalling each of his growth and success steps, i.e., beginning as a construction worker, obtained a certification of undergraduate learn by himself and a doctor’s degree in university, after then continuously overlooking these ...
openaire   +1 more source

Enumeration of E ( s 2 )‐Optimal and Minimax‐Optimal Supersaturated Designs With 12 Rows, 11 q Columns and s max = 4

open access: yesJournal 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

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