Proof of NP-completeness of the problem

Question

We are given the set A = {a ₁, a ₂, ..., a _n}

Specified Subsets A With Name B ₁, B ₂, ..., B _m. If a subset A named H has an intersection with all data of B, we call H “Covering subset”. Is there any “covering subset” of size K (cardinality H is K) for data A and Bs? Prove that this problem is NP-Complete.

We must reduce some well-known problem to the problem of "cover a subset."

Answer 1

update This is called a hit set . You can read the same answer in a Wikipedia article.

, , .

. {B1, B2, ...} - {a1, a2, ...} - . 'Set' ai 'element' Bj , set Bj ai .

"" ai, "" Bj. NP-, .

, , set/element /.

Bj ai
"" Bj "" ai