CALF Logo

Categorical

Automata

Learning

Framework

modular design and development of automata learning algorithms, with correctness-by-construction guarantees

2017

Learning Nominal Automata
We present an Angluin-style algorithm to learn nominal automata, which are acceptors of languages over infinite (structured) alphabets. The abstract approach we take allows us to seamlessly extend known variations of the algorithm to this new setting. In particular we can learn a subclass of nominal non-deterministic automata. An implementation using a recently developed Haskell library for nominal computation is provided for preliminary experiments.
Joshua Moerman, Matteo Sammartino, Alexandra Silva, Michał Szynwelsky, Bartek Klin
POPL
Learning Automata with Side-Effects
Automata learning has been successfully applied in the verification of hardware and software. The size of the automaton model learned is a bottleneck for scalability and hence optimizations that enable learning of compact representations are important. In this paper, we continue the development of a general framework for automata learning based on category theory and develop a class of optimizations and an accompanying correctness proof for learning algorithms. The new algorithm is parametric on a monad, which provides a rich algebraic structure to capture non-determinism and other side-effects. These side-effects are used to learn more compact automaton models and the abstract categorical approach enables us to capture several possible optimizations under the same (p)roof.
Gerco van Heerdt, Matteo Sammartino and Alexandra Silva
arXiv 1704.08055
CALF: Categorical Automata Learning Framework
Automata learning is a technique that has successfully been applied in verification, with the automaton type varying depending on the application domain. Adaptations of automata learning algorithms for increasingly complex types of automata have to be developed from scratch because there was no abstract theory offering guidelines. This makes it hard to devise such algorithms, and it obscures their correctness proofs. We introduce a simple category-theoretic formalism that provides an appropriately abstract foundation for studying automata learning. Furthermore, our framework establishes formal relations between algorithms for learning, testing, and minimization. We illustrate its generality with two examples: deterministic and weighted automata.
Gerco van Heerdt, Matteo Sammartino and Alexandra Silva
CSL
CALF: Categorical Automata Learning Framework (extended abstract)
Adaptations of automata learning algorithms for increas- ingly complex types of automata have to be developed from scratch because there is no abstract theory in place to guide the process. This makes it hard to devise such algorithms, and it obscures their correct- ness proofs. We introduce CALF, a simple category theoretical frame- work that provides an appropriately abstract foundation for studying automata learning and furthermore establishes formal relations between algorithms for learning, testing, and minimization.
Gerco van Heerdt, Matteo Sammartino and Alexandra Silva
LiVe (Learning in Verification)

2016

An Abstract Automata Learning Framework
Advanced applications of automata learning demand in- creasinly complex learning algorithms that are hard to reason about. We use the language of category theory to develop a unifying framework for the study of automata learning and show that by a slight generalization minimization and confor- mance testing are covered as well. The results are expected to inspire or even form the basis of new algorithms. As an example, we instantiate the framework to set the first steps towards an algorithm that learns nominal automata.
Gerco van Heerdt
Master Thesis, Radboud University Nijmegen

2014

Automata Learning: a Categorical Perspective
Automata learning is a known technique to infer a finite state machine from a set of observations. In this paper, we revisit Angluin’s original algorithm from a categorical perspective. This abstract view on the main ingredients of the algorithm lays a uniform framework to derive algorithms for other types of atomata. We show a straightforward generalization to Moore and Mealy machines, which yields an algorithm already known in the literature, and we discuss generalizations to other types of automata, including weighted automata.
Bart Jacobs and Alexandra Silva
Horizons of the Mind