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A Python package for automata theory.

Project description



Python implementation of automata theory.



pip install pythomata
  • or, from source (e.g. develop branch):
pip install git+
  • or, clone the repository and install:
git clone htts://
cd pythomata
pip install .

How to use

  • Define an automaton:
from pythomata import SimpleDFA
alphabet = {"a", "b", "c"}
states = {"s1", "s2", "s3"}
initial_state = "s1"
accepting_states = {"s3"}
transition_function = {
    "s1": {
        "b" : "s1",
        "a" : "s2"
    "s2": {
        "a" : "s3",
        "b" : "s1"
        "c" : "s3"
dfa = SimpleDFA(states, alphabet, initial_state, accepting_states, transition_function)
  • Test word acceptance:
# a word is a list of symbols
word = "bbbac"
dfa.accepts(word)        # True

# without the last symbol c, the final state is not reached
dfa.accepts(word[:-1])   # False
  • Operations such as minimization and trimming:
dfa_minimized = dfa.minimize()
dfa_trimmed = dfa.trim()
graph = dfa.minimize().trim().to_graphviz()

To print the automaton:


For that you will need to install Graphviz. Please look at their download page for detailed instructions depending on your system.

The output looks like the following:


  • Basic DFA and NFA support;
  • Algorithms for DFA minimization and trimming;
  • Algorithm for NFA determinization;
  • Translate automata into Graphviz objects.
  • Support for Symbolic Automata.


To run the tests:


To run only the code style checks:

tox -e flake8 -e mypy


To build the docs:

mkdocs build

To view documentation in a browser

mkdocs serve

and then go to http://localhost:8000


Pythomata is released under the GNU Lesser General Public License v3.0 or later (LGPLv3+).

Copyright 2018-2020 WhiteMech

Release History

0.3.1 (2020-02-28)

  • Improved CI: using GitHub actions instead of Travis.
  • Included many other checks: safety, black, liccheck.
  • Improved documentation.

0.3.0 (2020-02-09)

  • Main refactoring of the APIs.
  • Introduce interfaces for better abstractions: Alphabet, FiniteAutomaton etc.
  • DFA and NFA renamed SimpleDFA and SimpleNFA, respectively.
  • Introduced SymbolicAutomaton and SymbolicDFA, where the guards on transitions are propositoinal formulas.

0.2.0 (2019-09-30)

  • Refactoring of the repository

0.1.0 (2019-04-13)

  • Basic support for DFAs and NFAs.
  • Algorithms for DFA minimization and trimming.
  • Algorithm for NFA determinization.

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