npm i ts-automata

Check out dnbln's Agda package for Automata proofs: https://dnbln.dev/agdomaton

Overview

Currently supported are the Deterministic, Nondeterministic and Generalised nondeterministic finite state automata as well as nondeterministic push-down automata.

Make use of the provided TSDoc for insight on the methods.

Building and testing

After cloning the repo, you can use:

npm i            # to insteall dependencies

npm run build    # to build with tsc

npm run test     # to run tests

npm run coverage # to run tests with coverage

Usage

Automata can be created by choosing an alphabet to feed to the Automaton, defining the states of the automaton and finally the transition function. The code below is an example of creating and running input on a DFA.

/* Initialize the DFA */
const dfa = new DFA("ab", "q0", false);

/* Add states to the DFA */
dfa.addState("q1", false);
dfa.addState("q2", true);

/* Define the transition function for each state */
dfa.addEdge("q0", "b", "q0");
dfa.addEdge("q0", "a", "q1");
dfa.addEdge("q1", "a", "q2");
dfa.addEdge("q1", "b", "q0");
dfa.addEdge("q2", "a", "q2");
dfa.addEdge("q2", "b", "q2");

/* Check for validity */
console.log(dfa.isValid());

/* Run strings on the DFA */
dfa.runString("ababababaa"); // true
dfa.runString("aa"); // true
dfa.runString("abb"); // false

Figure 1: The code for the deterministic finite automaton D.

Figure 2: Visual representation of D.

This can also be done using the helpful DFABuilder:

const dfa = new DFABuilder("ab")
    /* Add states to the DFA */
    .withNotFinalStates("q0", "q1")
    .withFinalStates("q2")

    /* Define the transition function for each state */
    .withEdges.from("q0")
    .toSelf()
    .over("b")
    .withEdges.from("q0")
    .to("q1")
    .over("a")
    .withEdges.from("q1")
    .to("q2")
    .over("a")
    .withEdges.from("q1")
    .to("q0")
    .over("b")
    .withEdges.from("q2")
    .toSelf()
    .over("ab")
    .getResult();

Figure 3: Creating a DFA using a DFABuilder.

Roadmap

As of 27th June 2024

1. Turing machine simulation
2. CFG simulation and parsing
3. WriterSide documentation
4. GUI (out of scope for this repo)