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 test_input/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