py-aiger-sat

Pythonic interface between AIGs and SAT solvers.

Table of Contents

• Installation
• Usage

Installation

If you just need to use aiger_sat, you can just run:

$ pip install py-aiger-sat

For developers, note that this project uses the poetry python package/dependency management tool. Please familarize yourself with it and then run:

$ poetry install

Usage

aiger_sat has two seperate API's. The first, called the Object API, centers around the SolverWrapper object - a thin wrapper around a pysat solver. The second is a Function API which exposes 4 functions solve, is_sat, is_valid, and are_equiv. The function API is primarily useful for simple 1-off SAT instances, where as the object API is more useful when incremental solves are needed, or the underlying pysat solver must be exposed.

Object API

from aiger_sat import SolverWrapper

solver = SolverWrapper()  # defaults to Glucose4

from pysat.solvers import Glucose3
solver2 = SolverWrapper(solver=Glucose3)

solver operate on boolean expressions in the form of aiger circuits with a single output. For example,

import aiger

x, y, z = map(aiger.atom, ['x', 'y', 'z'])

expr = (x & y) | ~z
solver.add_expr(expr)
assert solver.is_sat()
model = solver.get_model()
print(model)  # {'x': True, 'y': False, 'z': False}
assert expr(model)

Further, aiger_sat supports making assumptions and computing unsat_cores.

# Make invalid assumption.
assert not solver.is_sat(assumptions={
    'x': False,
    'z': True,
})
assert not solver.unsolved

core = solver.get_unsat_core()
assert core == {'x': False, 'z': True}

Function API

import aiger
import aiger_sat

x, y, z = map(aiger.atom, ['x', 'y', 'z'])
assert aiger_sat.is_sat(x & y & z)

model = aiger_sat.solve(x & y & z)
assert model == {'x': True, 'y': True, 'z': True}

assert aiger_sat.is_valid(aiger.atom(True))

expr1 = x & y
expr2 = x & y & (z | ~z)
assert aiger_sat.are_equiv(expr1, expr2)

BitVector Support

py-aiger-sat also natively supports the py-aiger-bv bitvector library.

To enable this support, make sure that py-aiger-bv is installed, either manually:

$ pip install py-aiger-bv

or by installing py-aiger-sat with the bitvector option:

$ pip install py-aiger-sat[bitvector] or $ poetry install --extras=bitvector

Usage is analogous to the non-bitvector usage.

from aiger_bv import atom
from aiger_sat import sat_bv

# Object API
expr = atom(4, 'x') & atom(4, 'y') < 2
f = sat_bv.SolverBVWrapper()
f.add_expr(expr)

model = f.get_model()

# Function API.
model = sat_bv.solve(expr)

print(model)
# {'x': (False, False, True, True), 'y': (False, False, True, True)}