1. AM with Multiple Merlins
2. Proof verification and the hardness of approximation problems
3. Probabilistic checking of proofs
4. László Babai , Lance Fortnow , and Carsten Lund . 1991. Non-deterministic exponential time has two-prover interactive protocols. Computational complexity, 1, 1 ( 1991 ), 3–40. László Babai, Lance Fortnow, and Carsten Lund. 1991. Non-deterministic exponential time has two-prover interactive protocols. Computational complexity, 1, 1 (1991), 3–40.