Polynomial time approximation schemes for dense instances of NP-hard problems

We present a unified framework for designing polynomial time approximation schemes (PTASs) for “dense” instances of many NP-hard optimization problems, including maximum cut, graph bisection, graph separation, minimum k-way cut with and without specified terminals, and maximum 3-satisfiability. By dense graphs we mean graphs with minimum degree Ω(n), although our algorithms solve most of these problems so long as the average degree is Ω(n). Denseness for non-graph problems is defined similarly. The unified framework begins with the idea of exhaustive sampling: picking a small random set of vertices, guessing where they go on the optimum solution, and then using their placement to determine the placement of everything else. The approach then develops into a PTAS for approximating certain smooth integer programs where the objective function and the constraints are “dense” polynomials of constant degree.

• Type: Conference
• Year: 1995
• Where: STOC
• Authors: Sanjeev Arora, David R. Karger, Marek Karpinski
• Keywords: Algorithms, Minimum K-way Cut, NP-hard Optimization Problems, STOC 1995, Unified Framework