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AALpy is a light-weight active automata learning library written in pure Python. By implementing a single method and a few lines of configuration, you can start learning automata.
Whether you work with regular languages, or you would like to learn models of reactive systems, AALpy supports a wide range of modeling formalisms including deterministic, non-deterministic, and stochastic automata. You can use it to learn deterministic finite automata, Moore machines, and Mealy machines of deterministic systems. If the system that you would like to learn shows non-deterministic or stochastic behavior, AALpy allows you to learn observable nondeterministic finite-state machines, Markov decision processes, or stochastic transducers.
AALpy enables efficient learning by providing a large array of equivalence oracles, implementing various conformance testing strategies. Learning is mostly based on Angluin's L* algorithm, for which AALpy supports a selection of optimizations, including efficient counterexample processing. Finally, support for learning abstracted nondeterministic Mealy machines enables efficient learning of system models with large input space.
If you miss a specific feature in AALpy, you can easily extend it.
Use the package manager pip to install AALpy.
pip install aalpyMinimum required version of Python is 3.6.
Ensure that you have Graphviz installed and added to your path if you want to visualize models.
For manual installation clone the master and install the following dependency.
pip install pydot
# and to install the library
python setup.py installIf you are interested in automata learning or would like to understand the automata learning process in more detail, please check out our Wiki. On Wiki, you will find more detailed examples on how to use AALpy.
For the official documentation of all classes and methods check out:
Interactive examples can be found in the notebooks folder. If you would like to interact/change those examples in the browser, click on the following badge.
In Examples.py, many examples demonstrating all AALpy functionality are presented.
All automata learning procedures follow this high-level approach:
- Define the input alphabet and system under learning (SUL)
- Choose the equivalence oracle
- Run the learning algorithm
The following snippet demonstrates a short example in which an automaton is either loaded or randomly generated and then learned.
from aalpy.utils import load_automaton_from_file, save_automaton_to_file, visualize_automaton, generate_random_dfa
from aalpy.SULs import DfaSUL
from aalpy.oracles import RandomWalkEqOracle, StatePrefixEqOracle
from aalpy.learning_algs import run_Lstar
# load an automaton
automaton = load_automaton_from_file('path_to_the_file.dot')
# or randomly generate one
random_dfa = generate_random_dfa(alphabet=[1,2,3,4,5],num_states=2000, num_accepting_states=200)
# get input alphabet of the automaton
alphabet = random_dfa.get_input_alphabet()
# create a SUL instance for the automaton/system under learning
sul = DfaSUL(random_dfa)
# define the equivalence oracle
eq_oracle = RandomWalkEqOracle(alphabet, sul, num_steps=5000, reset_prob=0.09)
eq_oracle_2 = StatePrefixEqOracle(alphabet, sul, walks_per_state=20, walk_len=10)
# start learning
learned_dfa = run_Lstar(alphabet, sul, eq_oracle, automaton_type='dfa')
# save automaton to file and visualize it
save_automaton_to_file(learned_dfa, path='Learned_Automaton', file_type='dot')
visualize_automaton(learned_dfa)In order to make experiments reproducible, simply define a random seed at the beginning of your program.
from random import seed
seed(2) # all experiments will be reproducibleAnother example shows how easy it is to learn a regular expression with AALpy. For more details on this example take a look at - How to learn Regex with AALpy
from aalpy.oracles import StatePrefixEqOracle
from aalpy.SULs import RegexSUL
from aalpy.learning_algs import run_Lstar
regex = 'abc(b|c)+(ab|c)*'
alphabet = ['a', 'b', 'c']
regex_sul = RegexSUL(regex)
eq_oracle = StatePrefixEqOracle(alphabet, regex_sul, walks_per_state=100,
walk_len=20)
learned_regex = run_Lstar(alphabet, regex_sul, eq_oracle, automaton_type='dfa', print_level=2)
visualize_automaton(learned_regex)This code snippet results in:
Hypothesis 1 has 1 states.
Hypothesis 2 has 7 states.
Hypothesis 3 has 8 states.
-----------------------------------
Learning Finished.
Learning Rounds: 3
Number of states: 8
Time (in seconds)
Total : 0.05
Learning algorithm : 0.0
Conformance checking : 0.05
Learning Algorithm
# Membership Queries : 85
# MQ Saved by Caching : 120
# Steps : 582
Equivalence Query
# Membership Queries : 800
# Steps : 18173
-----------------------------------
and
