combinatorial bounds 1cross-intersection 1extremal combinatorics 1intersecting families 1set systems 1
From the 1 of 3 linked papers with an AI index.
3 papers
math.CO2026
On nontrivial cross-2-intersecting families
Jingjun Bao, Lijun Ji, Liying Yu
The paper determines the maximum possible product of the sizes of two nontrivial cross‑2‑intersecting families of k‑ and ℓ‑subsets of an n‑element set, and describes the families t…
math.CO2025
The maximum product of sizes of cross-\(t\)-intersecting families
Jingjun Bao, Lijun Ji
Two families of sets \(\mathcal{A}\) and \(\mathcal{B}\) are called \emph{cross-\(t\)-intersecting} if \(|A \cap B| \geq t\) for all \(A \in \mathcal{A}\) and \(B \in \mathcal{B}\)…
math.CO2025
New Necessary Conditions for Existence of Strong External Difference Families
Jingjun Bao, Lijun Ji
Strong external difference families (SEDFs) were introduced by Paterson and Stinson as a more restrictive version of external difference families. SEDFs can be used to produce opti…