Extremal Graph Theoretic Questions for q-Ary Vectors
Open Access
- 24 April 2024
- journal article
- research article
- Published by Springer Nature in Graphs and Combinatorics
- Vol. 40 (3) , 1-21
Abstract
A q-graph H on n vertices is a set of vectors of length n with all entries from $$\{0,1,\dots ,q\}$$ and every vector (that we call a q-edge) having exactly two non-zero entries. The support of a q-edge $${\textbf{x}}$$ is the pair $$S_{\textbf{x}}$$ of indices of non-zero entries. We say that H is an s-copy of an ordinary graph F if $$|H|=|E(F)|$$ , F is isomorphic to the graph with edge set $$\{S_{\textbf{x}}:{\textbf{x}}\in H\}$$ , and whenever $$v\in e,e'\in E(F)$$ , the entries with index corresponding to v in the q-edges corresponding to e and $$e'$$ sum up to at least s. E.g., the q-edges (1, 3, 0, 0, 0), (0, 1, 0, 0, 3), and (3, 0, 0, 0, 1) form a 4-triangle. The Turán number $$\mathop {}\!\textrm{ex}(n,F,q,s)$$ is the maximum number of q-edges that a q-graph H on n vertices can have if it does not contain any s-copies of F. In the present paper, we determine the asymptotics of $$\mathop {}\!\textrm{ex}(n,F,q,q+1)$$ for many graphs F.
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Funding Information
- NKFIH (SNN 129 364, FK 132060)
This publication has 4 references indexed in Scilit:
- Vector sum-intersection theoremsDiscrete Mathematics, 2023
- The History of Degenerate (Bipartite) Extremal Graph Problems2013
- On a problem of K. ZarankiewiczColloquium Mathematicum, 1954
- On the structure of linear graphsBulletin of the American Mathematical Society, 1946