Nearly extremal non-trivial cross t-intersecting families and r-wise t-intersecting families

Let n, r, k1,…,kr and t be positive integers with r≥2, and Fi(1≤i≤r) a family of ki-subsets of an n-set V. The families F1,F2,…,Fr are said to be r-cross t-intersecting if |F1∩F2∩⋯∩Fr|≥t for all Fi∈Fi(1≤i≤r), and said to be non-trivial if |∩1≤i≤r∩F∈FiF|更多