Intersecting and Cross-Intersecting Families of Labeled Sets
Intersecting and Cross-Intersecting Families of Labeled Sets
A family ${\cal A}$ of sets is said to be intersecting if any two sets in ${\cal A}$ intersect. Families ${\cal A}_1, ..., {\cal A}_p$ are said to be cross-intersecting if, for any $i, j \in \{1, ..., p\}$ such that $i \neq j$, any set in ${\cal A}_i$ intersects …