Complex sentence: There are some problems in both NP and co-NP, for example all problems in P or integer factorization; however, it is not known if the sets are equal, although inequality is thought more likely.
Split into simpler sentences: There are some problems in both NP and co-NP, for example all problems in P or integer factorization. However, it is not known if the sets are equal, although inequality is thought more likely.