arXiv subjects

Amazigh Amrane

Publications and source records attributed to Amazigh Amrane.

9 recordsLinked to original sources

arXiv2026

Higher-Dimensional Automata : Extension to Infinite Tracks

We introduce higher-dimensional automata for infinite interval ipomsets ($ω$-HDAs). We define key concepts from different points of view, inspired from their finite counterparts. Then we explore languages recognized by $ω$-HDAs under Büchi and Muller semantics. We show that Muller acceptance is more expressive than Büchi acceptance and, in contrast to the finite case, both semantics do not yield languages closed under subsumption. Then, we adapt the original rational operations to deal with $ω$-HDAs and show that while languages of $ω$-HDAs are $ω$-rational, not all $ω$-rational languages can be expressed by $ω$-HDAs.

cs.FL↗

arXiv2026

Active Learning Techniques for Pomset Recognizers

Pomsets are a promising formalism for concurrent programs based on partially ordered sets. Among this class, series-parallel pomsets admit a convenient linear representation and can be recognized by simple algebraic structures known as pomset recognizers. Active learning consists in inferring a formal model of a recognizable language by asking membership and equivalence queries to a minimally adequate teacher (MAT). We improve existing learning algorithms for pomset recognizers by 1. introducing a new counter-example analysis procedure that is in the best case scenario exponentially more efficient than existing methods 2. adapting the state-of-the-art $L^λ$ algorithm to minimize the impact of exceedingly verbose counter-examples and remove redundant queries 3. designing a suitable finite test suite that ensures general equivalence between two pomset recognizers by extending the well-known W-method.

cs.FL↗

arXiv2025

Büchi-Elgot-Trakhtenbrot Theorem for Higher-Dimensional Automata

In this paper we explore languages of higher-dimensional automata (HDAs) from an algebraic and logical point of view. Such languages are sets of finite width-bounded interval pomsets with interfaces (ipomsets) closed under order extension. We show that ipomsets can be represented as equivalence classes of words over a particular alphabet, called step sequences. We introduce an automaton model that recognize such languages. Doing so allows us to lift the classical Büchi-Elgot-Trakhtenbrot Theorem to languages of HDAs: we prove that a set of interval ipomsets is the language of an HDA if and only if it is simultaneously MSO-definable, of bounded width, and closed under order refinement.

cs.FL↗

arXiv2025

Higher-Dimensional Timed Automata for Real-Time Concurrency

We present a new language semantics for real-time concurrency. Its operational models are higher-dimensional timed automata (HDTAs), a generalization of both higher-dimensional automata and timed automata. In real-time concurrent systems, both concurrency of events and timing and duration of events are of interest. Thus, HDTAs combine the non-interleaving concurrency model of higher-dimensional automata with the real-time modeling, using clocks, of timed automata. We define languages of HDTAs as sets of interval-timed pomsets with interfaces. We show that language inclusion of HDTAs is undecidable. On the other hand, using a region construction we can show that untimings of HDTA languages have enough regularity so that untimed language inclusion is decidable. On a more practical note, we give new insights on when practical applications, like checking reachability, might benefit from using HDTAs instead of classical timed automata.

cs.FL↗

arXiv2025

Petri Nets and Higher-Dimensional Automata

Petri nets and their variants are often considered through their interleaved semantics, i.e. considering executions where, at each step, a single transition fires. This is clearly a miss, as Petri nets are a true concurrency model. This paper revisits the semantics of Petri nets as higher-dimensional automata (HDAs) as introduced by van Glabbeek, which methodically take concurrency into account. We extend the translation to include some common features. We consider nets with inhibitor arcs, under both concurrent semantics used in the literature, and generalized self-modifying nets. Finally, we present a tool that implements our translations.

cs.LO↗

arXiv2024

Closure and Decision Properties for Higher-Dimensional Automata

We report some further developments regarding the language theory of higher-dimensional automata (HDAs). Regular languages of HDAs are sets of finite interval partially ordered multisets (pomsets) with interfaces. We show a pumping lemma which allows us to expose a class of non-regular languages. Concerning decision and closure properties, we show that inclusion of regular languages is decidable (hence is emptiness), and that intersections of regular languages are again regular. On the other hand, complements of regular languages are not always regular. We introduce a width-bounded complement and show that width-bounded complements of regular languages are again regular. We also study determinism and ambiguity. We show that it is decidable whether a regular language is accepted by a deterministic HDA and that there exists regular languages with unbounded ambiguity. Finally, we characterize one-letter deterministic languages in terms of utlimately periodic functions.

cs.FL↗

arXiv2024

Presenting Interval Pomsets with Interfaces

Interval-order partially ordered multisets with interfaces (ipomsets) have shown to be a versatile model for executions of concurrent systems in which both precedence and concurrency need to be taken into account. In this paper, we develop a presentation of ipomsets as generated by a graph of certain discrete ipomsets (starters and terminators) under the relation which composes subsequent starters and subsequent terminators. Using this presentation, we show that also subsumptions are generated by elementary relations. We develop a similar correspondence on the automata side, relating higher-dimensional automata, which generate ipomsets, and ST-automata, which generate step sequences, and their respective languages.

cs.FL↗

arXiv2024

Logic and Languages of Higher-Dimensional Automata

In this paper we study finite higher-dimensional automata (HDAs) from the logical point of view. Languages of HDAs are sets of finite bounded-width interval pomsets with interfaces (iiPoms<=k) closed under order extension. We prove that languages of HDAs are MSO-definable. For the converse, we show that the order extensions of MSO-definable sets of iiPoms<=k are languages of HDAs. As a consequence, unlike the case of all pomsets, order extension of MSO-definable sets of iiPoms<=k is also MSO-definable.

cs.FL↗

arXiv2019

Logic and Rational Languages of Scattered and Countable Series-Parallel Posets

Let $A$ be an alphabet and $SP^\diamond(A)$ denote the class of all countable N-free partially ordered sets labeled by $A$, in which chains are scattered linear orderings and antichains are finite. We characterize the rational languages of $SP^\diamond(A)$ by means of logic. We define an extension of monadic second-order logic by Presburger arithmetic, named P-MSO, such that a language $L$ of $SP^\diamond(A)$ is rational if and only if $L$ is the language of a sentence of P-MSO, with effective constructions from one formalism to the other. As a corollary, the P-MSO theory of $SP^\diamond(A)$ is decidable.

cs.LO↗