Probabilistic Checking of Proofs; A New Characterization of NP

We give a new characterization of NP: the class NP contains exactly those languages L for which membership proofs (a proof that an input x is in L) can be verified probabilistically in polynomial time using logarithmic number of random bits and by reading sublogarithmic number of bits from the proof. We discuss implications of this characterization; specifically, we show that approximating Clique and Independent Set, even in a very weak sense, is NP-hard.

• Type: Conference
• Year: 1992
• Where: FOCS
• Authors: Sanjeev Arora, Shmuel Safra
• Keywords: Class Np, FOCS 1992, Logarithmic Number, Random Bits, Theoretical Computer Science