We are given a set of names and a set of papers with names written on each side of the paper (not necessarily different ones and either side of the paper can be empty). Can we place the sheets on a table such that every name shows up? Show that this problem is NP-complete.
I have difficulty in finding out an NP-complete problem from which it can be reduced to this problem.
I tried to reduce vertex cover and set cover problems but i was not successful. I am not sure if i am heading in the right direction.