Constraint Satisfaction Problems with Advice
Suprovat Ghoshal, Konstantin Makarychev, Yury Makarychev
TL;DR
This work investigates constraint satisfaction problems with ML oracle advice, introducing Label Advice and Variable Subset Advice models and showing near-optimal algorithms for Max Cut, Max 2-Lin, and nearly satisfiable Max 3-Lin when the average degree is sufficiently large. It pairs these algorithmic results with ETH- and PCP-based hardness, proving that without degree guarantees Max $3$-Lin remains hard to beat beyond $1/2$ and that Max $4$-Lin is hard even under high-degree regimes. The authors leverage quadratic-form optimization, Goemans–Williamson, and reductions from Gap Label Cover to translate advice into algorithmic gains and to establish tight limits, highlighting when ML advice is most effective in CSPs. Collectively, the results delineate the boundary between when oracle advice yields substantial gains and when fundamental complexity barriers persist, guiding future exploration of ML-assisted CSP algorithms and their scalability.
Abstract
We initiate the study of algorithms for constraint satisfaction problems with ML oracle advice. We introduce two models of advice and then design approximation algorithms for Max Cut, Max $2$-Lin, and Max $3$-Lin in these models. In particular, we show the following. 1. For Max-Cut and Max $2$-Lin, we design an algorithm that yields near-optimal solutions when the average degree is larger than a threshold degree, which only depends on the amount of advice and is independent of the instance size. We also give an algorithm for nearly satisfiable Max $3$-Lin instances with quantitatively similar guarantees. 2. Further, we provide impossibility results for algorithms in these models. In particular, under standard complexity assumptions, we show that Max $3$-Lin is still $1/2 + η$ hard to approximate given access to advice, when there are no assumptions on the instance degree distribution. Additionally, we also show that Max $4$-Lin is $1/2 + η$ hard to approximate even when the average degree of the instance is linear in the number of variables.
