afsolver

A lightweight Python solver for Dung-style abstract argumentation framework (AF) semantics: conflict-free, admissible, complete, preferred, grounded, and stable.

Install

uv add afsolver

or with pip:

pip install afsolver

Quick start

from afsolver import ArgumentationFramework

af = ArgumentationFramework(
    arguments=["a", "b", "c"],
    attacks=[("a", "b"), ("b", "a"), ("c", "b")],  # a<->b mutual attack, c attacks b
)

af.preferred()   # [frozenset({'a', 'c'})]
af.grounded()    # frozenset({'a', 'c'})
af.extensions()  # dict with all six semantics at once

arguments is optional — if omitted, arguments are inferred from the attacks pairs (deduplicated, in order of first appearance):

af = ArgumentationFramework(attacks=[("b", "a"), ("c", "b"), ("d", "c")])
af.arguments  # ('b', 'a', 'c', 'd')

Attack pairs can be tuples or lists — both are accepted and normalized to tuples internally.

API

ArgumentationFramework(arguments=(), attacks=())

preferred with a contains filter

Restrict the preferred extensions to those that include a given argument (or set of arguments) — useful for credulous-acceptance-style queries:

af = ArgumentationFramework(
    ["a", "b", "c", "d", "e"],
    [("b", "a"), ("c", "b"), ("d", "b"), ("c", "e"), ("e", "c")],
)

af.preferred()                     # [{'a', 'c', 'd'}, {'a', 'd', 'e'}]
af.preferred(contains=["a", "c"])  # [{'a', 'c', 'd'}]

minimal_admissible

Useful for finding the smallest admissible sets that justify including a given argument (or set of arguments):

af = ArgumentationFramework(
    ["a", "b", "c", "d", "e"],
    [("b", "a"), ("c", "b"), ("d", "b"), ("c", "e"), ("e", "c")],
)

af.minimal_admissible()                # [{'c'}, {'d'}, {'e'}]
af.minimal_admissible(contains=["a"])  # [{'a', 'c'}, {'a', 'd'}]

The empty set is always excluded — it's trivially admissible and a subset of everything else, so including it would hide the smallest non-trivial results.

Development

uv sync            # install project + dev dependencies
uv run pytest -q   # run tests
uv build           # build sdist + wheel