Theorem 4 (Frankl-Wilson Theorem). Assuming that:

  • p is prime

  • λ1,…,λs (s≤r)

  • λi⁄≡r(modp) for each i

  • A⊂X(r) such that for all distinct x,y∈A have |x∩y|≡λi(modp) for some i

Then |A|≤ns.