Question 18
The EXACT-COVER-BY-3-SETS problem is defined as the following: given a finite set with and a collection of 3-element subsets of , does contain an exact cover for , that is, a subcollection such that every element of occurs in exactly one member of ?
The EXACT-COVER-BY-4-SETS problem is defined as the following: given a finite set with and a collection of 4-element subsets of , does contain an exact cover for , that is, a subcollection such that every element of occurs in exactly one member of ?
Given that EXACT-COVER-BY-3-SETS is NP-Complete, is EXACT-COVER-BY-4-SETS also NP-Complete?
Yes, because there is a reduction from EXACT-COVER-BY-3-SETS to EXACT- COVER-BY-4-SETS.
Yes, because there is a reduction from EXACT-COVER-BY-4-SETS to EXACT- COVER-BY-3-SETS.
EXACT-COVER-BY-4-SETS may or may not be NP-Complete.