pycosat

0.6.6 verified Sat May 09 auth: no python maintenance

Python bindings to PicoSAT, a popular SAT solver written in C. Version 0.6.6 is the latest. The library is mature but receives infrequent updates; it is in maintenance mode.

pip install pycosat

Common errors

error AttributeError: module 'pycosat' has no attribute 'solve' ↓

cause pycosat does not expose a `solve` function; use `itersolve` or `blocksolve` instead.

fix

Use next(pycosat.itersolve(cnf)) or list(pycosat.itersolve(cnf)).

error MemoryError: Unable to allocate ... ↓

cause pycosat uses the PicoSAT library which may allocate large arrays for huge CNF formulas. Also, a memory leak in versions <0.6.4 could cause OOM.

fix

Upgrade to 0.6.4+ and consider splitting the problem into smaller chunks.

Warnings

deprecated The function `solve` is not available; use `itersolve` or `blocksolve`. ↓

fix Replace `pycosat.solve(...)` with `next(pycosat.itersolve(...))` for a single solution.

breaking In version 0.6.4, a memory leak was fixed in `blocksolve()`. If you rely on heavy iteration, upgrade to avoid cumulative memory usage. ↓

fix Upgrade to 0.6.4 or later: `pip install --upgrade pycosat`.

gotcha pycosat only accepts DIMACS CNF format, not other SAT formats like DIMACS WCNF or OPB. Variables must be positive integers. ↓

fix Convert your problem to DIMACS CNF (list of lists of non-zero integers, no 0).

Imports

itersolve
wrong
```
from pycosat import solve
```
correct
```
from pycosat import itersolve
```
itersolve is the generator version; solve is not a public function in pycosat.

Quickstart

Solve a simple CNF SAT problem using the generator itersolve.

import pycosat
# Solve a SAT problem: each clause is a list of integers
cnf = [[1, -2], [-1, 3], [-2, -3]]
solution = pycosat.itersolve(cnf)
for sol in solution:
    print(sol)