Core Concepts
The paper demonstrates a flaw in the algorithm presented in "A polynomial-time algorithm for 3-SAT" by Lizhi Du, which incorrectly identifies certain satisfiable 3-CNF boolean formulas as unsatisfiable.
Abstract
The paper provides a critique of the claims made in Lizhi Du's paper "A polynomial-time algorithm for 3-SAT". The key points are:
- Du's paper claims to provide a polynomial-time algorithm for solving the NP-complete 3-SAT problem, which would imply P = NP.
- The paper introduces relevant terminology and algorithms from Du's work, including the concept of a "standard checking tree" and "indirect contradiction pairs".
- The authors identify a flaw in Du's "Algorithm 1", which is used to repair a "destroyed checking tree" and determine the satisfiability of the 3-CNF formula.
- The authors provide a counterexample that demonstrates how Algorithm 1 can incorrectly conclude that certain satisfiable 3-CNF formulas are unsatisfiable, by incorrectly identifying "indirect contradiction pairs".
- Since the flaw is in a fundamental component of Du's algorithm, the authors argue that the entire algorithm does not correctly decide 3-SAT, and thus Du's claim of P = NP is not supported by the paper's arguments.