Outsourcing Computation: the Minimal Refereed Mechanism

TL;DR

This paper introduces the Minimal Refereed Mechanism, enabling a verifier with limited resources to delegate complex computations to rational provers who are incentivized to be honest, ensuring correctness without verification effort.

Contribution

The paper presents a novel mechanism that ensures honest computation reporting from rational provers with minimal verifier effort and logarithmic resource overhead.

Findings

Provers are incentivized to be honest under the mechanism.

Verifier's computational effort is logarithmic in input size.

Mechanism is efficient for low-space computations.

Abstract

We consider a setting where a verifier with limited computation power delegates a resource intensive computation task---which requires a $T\times S$ computation tableau---to two provers where the provers are rational in that each prover maximizes their own payoff---taking into account losses incurred by the cost of computation. We design a mechanism called the Minimal Refereed Mechanism (MRM) such that if the verifier has $O(\log S + \log T)$ time and $O(\log S + \log T)$ space computation power, then both provers will provide a honest result without the verifier putting any effort to verify the results. The amount of computation required for the provers (and thus the cost) is a multiplicative $\log S$-factor more than the computation itself, making this schema efficient especially for low-space computations.