simple-sat: Simple Python SAT Solver
This project is a simple recursive and iterative implementation of a backtracking, watchlist-based, SAT solver. Code is based mostly on Knuth's SAT0W program which can be found here. The iterative code follows Knuth's version much closer, but is a bit more complicated. The recursive version is rather straight-forward. Intended primarily to as a learning tool.
Accompanying article can be found at http://sahandsaba.com/understanding-sat-by-implementing-a-simple-sat-solver-in-python.html.
usage: sat.py [-h] [-v] [-a] [-b] [--output_filter OUTPUT_FILTER] [-r] [-i INPUT] Solve SAT instance by reading from stdin using an iterative or recursive watchlist-based backtracking algorithm. Iterative algorithm is used by default, unless the -r flag is given. Empty lines and lines starting with a # will be ignored. optional arguments: -h, --help show this help message and exit -v, --verbose verbose output. -a, --all output all possible solutions. -b, --brief brief output for assignemnts: outputs variables assigned 1. --output_filter OUTPUT_FILTER only output variables with namesstring with given string. -r, --recursive use the recursive backtracking algorithm. -i INPUT, --input INPUT read from given file instead of stdin.
$ python sat.py -v --input tests/simple/02.in Current watchlist: 1: 1 2 3, 1 ~2 ~1: 2: ~2: 3: ~3: ~1 ~3 Current assignment: ~1 ~2 ~3 Clause ~1 ~3 contradicted. Found satisfying assignment. ~1 ~2 3