marijnheule / ddcnf-demo

Demo of delta debugging for CNF formulas

ddcnf-demo

Demo of delta debugging for CNF formulas

introduction

The repository contains a buggy version of the SAT solver CaDiCaL. The file buggy-cadical/src/cadical.cpp was modified to incorrectly print the solution by adding a line to the App::print_witness procedure:

if (tmp % 100 == 33) tmp = -tmp; // bug

The demo shows the effectiveness of the delta debugger to find this bug.

installation and running

First compile all the sources:

./init.sh

Afterwards run the demo code

./demo.sh

demo output

The demo first runs the buggy CaDiCaL on a graph coloring problem 2550 variables and 13030 clauses

++ ./run.sh cnf/510-5.cnf c ERROR: clause 47 not satisfied

Afterwards it runs the delta debugger to reduce the size of the formula. The tool produces a smaller formula called output.cnf with only just one clause. It produces the same ERROR.

++ cat output.cnf p cnf 2550 1 33 0 ++ ./run.sh output.cnf c ERROR: clause 1 not satisfied