Ashwani Anand, Sylvain Schmitz, Lia Schütze, Georg Zetzsche
{"title":"Verifying Unboundedness via Amalgamation","authors":"Ashwani Anand, Sylvain Schmitz, Lia Schütze, Georg Zetzsche","doi":"arxiv-2405.10296","DOIUrl":"https://doi.org/arxiv-2405.10296","url":null,"abstract":"Well-structured transition systems (WSTS) are an abstract family of systems\u0000that encompasses a vast landscape of infinite-state systems. By requiring a\u0000well-quasi-ordering (wqo) on the set of states, a WSTS enables generic\u0000algorithms for classic verification tasks such as coverability and termination.\u0000However, even for systems that are WSTS like vector addition systems (VAS), the\u0000framework is notoriously ill-equipped to analyse reachability (as opposed to\u0000coverability). Moreover, some important types of infinite-state systems fall\u0000out of WSTS' scope entirely, such as pushdown systems (PDS). Inspired by recent algorithmic techniques on VAS, we propose an abstract\u0000notion of systems where the set of runs is equipped with a wqo and supports\u0000amalgamation of runs. We show that it subsumes a large class of infinite-state\u0000systems, including (reachability languages of) VAS and PDS, and even all\u0000systems from the abstract framework of valence systems, except for those\u0000already known to be Turing-complete. Moreover, this abstract setting enables simple and general algorithmic\u0000solutions to unboundedness problems, which have received much attention in\u0000recent years. We present algorithms for the (i) simultaneous unboundedness\u0000problem (which implies computability of downward closures and decidability of\u0000separability by piecewise testable languages), (ii) computing priority downward\u0000closures, (iii) deciding whether a language is bounded, meaning included in\u0000$w_1^*cdots w_k^*$ for some words $w_1,ldots,w_k$, and (iv)~effective\u0000regularity of unary languages. This leads to either drastically simpler proofs\u0000or new decidability results for a rich variety of systems.","PeriodicalId":501124,"journal":{"name":"arXiv - CS - Formal Languages and Automata Theory","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141061016","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Extended time Petri nets","authors":"Marcin Radom, Piotr Formanowicz","doi":"arxiv-2405.09208","DOIUrl":"https://doi.org/arxiv-2405.09208","url":null,"abstract":"In many complex systems that can be modeled using Petri nets time can be a\u0000very important factor which should be taken into account during creation and\u0000analysis of the model. Time data can describe starting moments of some actions\u0000or their duration before their immediate effects start to influence some other\u0000areas of the modeled system. Places in a Petri net often describe static\u0000components of the system, but they can also describe states. Such a state can\u0000have time restrictions, for example, telling how long it can influence other\u0000elements in the model. Time values describing some system may be inconsistent\u0000or incomplete, which can cause problems during the creation of the model. In\u0000this paper, a new extension of time Petri nets is proposed, which allows the\u0000creation of models with different types of time data, which previously were\u0000possible to be properly used in separate types of well-known time Petri nets.\u0000The proposed new time Petri net solves this problem by integrating different\u0000aspects of already existing time Petri nets into one unified net.","PeriodicalId":501124,"journal":{"name":"arXiv - CS - Formal Languages and Automata Theory","volume":"131 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141061028","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Paolo BallariniMICS, Mahmoud Bentriou, Paul-Henry Cournède
{"title":"A Formal Approach for Tuning Stochastic Oscillators","authors":"Paolo BallariniMICS, Mahmoud Bentriou, Paul-Henry Cournède","doi":"arxiv-2405.09183","DOIUrl":"https://doi.org/arxiv-2405.09183","url":null,"abstract":"Periodic recurrence is a prominent behavioural of many biological phenomena,\u0000including cell cycle and circadian rhythms. Although deterministic models are\u0000commonly used to represent the dynamics of periodic phenomena, it is known that\u0000they are little appropriate in the case of systems in which stochastic noise\u0000induced by small population numbers is actually responsible for periodicity.\u0000Within the stochastic modelling settings automata-based model checking\u0000approaches have proven an effective means for the analysis of oscillatory\u0000dynamics, the main idea being that of coupling a period detector automaton with\u0000a continuous-time Markov chain model of an alleged oscillator. In this paper we\u0000address a complementary aspect, i.e. that of assessing the dependency of\u0000oscillation related measure (period and amplitude) against the parameters of a\u0000stochastic oscillator. To this aim we introduce a framework which, by combining\u0000an Approximate Bayesian Computation scheme with a hybrid automata capable of\u0000quantifying how distant an instance of a stochastic oscillator is from matching\u0000a desired (average) period, leads us to identify regions of the parameter space\u0000in which oscillation with given period are highly likely. The method is\u0000demonstrated through a couple of case studies, including a model of the popular\u0000Repressilator circuit.","PeriodicalId":501124,"journal":{"name":"arXiv - CS - Formal Languages and Automata Theory","volume":"33 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141061001","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Containment Problem for Deterministic Multicounter Machine Models","authors":"Oscar H. Ibarra, Ian McQuillan","doi":"arxiv-2405.08988","DOIUrl":"https://doi.org/arxiv-2405.08988","url":null,"abstract":"There are many types of automata and grammar models that have been studied in\u0000the literature, and for these models, it is common to determine whether certain\u0000problems are decidable. One problem that has been difficult to answer\u0000throughout the history of automata and formal language theory is to decide\u0000whether a given system $M$ accepts a bounded language (whether there exist\u0000words $w_1, ldots,w_k$ such that $L(M) subseteq w_1^* cdots w_k^*$?).\u0000Boundedness was only known to be decidable for regular and context-free\u0000languages until recently when it was shown to also be decidable for finite\u0000automata and pushdown automata augmented with reversal-bounded counters, and\u0000for vector addition systems with states. However, decidability of this problem\u0000has still gone unanswered for the majority of automata/grammar models with a\u0000decidable emptiness problem that have been studied in the literature. In this paper, we develop new techniques to show that the boundedness problem\u0000is decidable for larger classes of one-way nondeterministic automata and\u0000grammar models by reducing the problem to the decidability of boundedness for\u0000simpler classes of automata. One technique involves characterizing the models\u0000in terms of multi-tape automata. We give new characterizations of finite-turn\u0000Turing machines, finite-turn Turing machines augmented with various storage\u0000structures (like a pushdown, multiple reversal-bounded counters,\u0000partially-blind counters, etc.), and simple matrix grammars. The\u0000characterizations are then used to show that the boundedness problem for these\u0000models is decidable. Another technique uses the concept of the store language\u0000of an automaton. This is used to show that the boundedness problem is decidable\u0000for pushdown automata that can \"flip\" their pushdown a bounded number of times.\u0000Boundedness remains decidable even if we augment this device with additional\u0000stores.","PeriodicalId":501124,"journal":{"name":"arXiv - CS - Formal Languages and Automata Theory","volume":"48 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141061061","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Martin Berglund, Willeke Martens, Brink van der Merwe
{"title":"Constructing a BPE Tokenization DFA","authors":"Martin Berglund, Willeke Martens, Brink van der Merwe","doi":"arxiv-2405.07671","DOIUrl":"https://doi.org/arxiv-2405.07671","url":null,"abstract":"Many natural language processing systems operate over tokenizations of text\u0000to address the open-vocabulary problem. In this paper, we give and analyze an\u0000algorithm for the efficient construction of deterministic finite automata\u0000designed to operate directly on tokenizations produced by the popular byte pair\u0000encoding technique. This makes it possible to apply many existing techniques\u0000and algorithms to the tokenized case, such as pattern matching, equivalence\u0000checking of tokenization dictionaries, and composing tokenized languages in\u0000various ways.","PeriodicalId":501124,"journal":{"name":"arXiv - CS - Formal Languages and Automata Theory","volume":"160 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140938308","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Gödel Number based Clustering Algorithm with Decimal First Degree Cellular Automata","authors":"Vicky Vikrant, Narodia Parth P, Kamalika Bhattacharjee","doi":"arxiv-2405.04881","DOIUrl":"https://doi.org/arxiv-2405.04881","url":null,"abstract":"In this paper, a decimal first degree cellular automata (FDCA) based\u0000clustering algorithm is proposed where clusters are created based on\u0000reachability. Cyclic spaces are created and configurations which are in the\u0000same cycle are treated as the same cluster. Here, real-life data objects are\u0000encoded into decimal strings using G\"odel number based encoding. The benefits\u0000of the scheme is, it reduces the encoded string length while maintaining the\u0000features properties. Candidate CA rules are identified based on some\u0000theoretical criteria such as self-replication and information flow. An\u0000iterative algorithm is developed to generate the desired number of clusters\u0000over three stages. The results of the clustering are evaluated based on\u0000benchmark clustering metrics such as Silhouette score, Davis Bouldin, Calinski\u0000Harabasz and Dunn Index. In comparison with the existing state-of-the-art\u0000clustering algorithms, our proposed algorithm gives better performance.","PeriodicalId":501124,"journal":{"name":"arXiv - CS - Formal Languages and Automata Theory","volume":"2 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140938303","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Probabilistic Finite Automaton Emptiness is undecidable","authors":"Günter Rote","doi":"arxiv-2405.03035","DOIUrl":"https://doi.org/arxiv-2405.03035","url":null,"abstract":"It is undecidable whether the language recognized by a probabilistic finite\u0000automaton is empty. Several other undecidability results, in particular\u0000regarding problems about matrix products, are based on this important theorem.\u0000We present two proofs of this theorem from the literature in a self-contained\u0000way, and we derive some strengthenings. For example, we show that the problem\u0000remains undecidable for a fixed probabilistic finite automaton with 11 states,\u0000where only the starting distribution is given as input.","PeriodicalId":501124,"journal":{"name":"arXiv - CS - Formal Languages and Automata Theory","volume":"12 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140881567","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"A Direct Translation from LTL with Past to Deterministic Rabin Automata","authors":"Shaun Azzopardi, David Lidell, Nir Piterman","doi":"arxiv-2405.01178","DOIUrl":"https://doi.org/arxiv-2405.01178","url":null,"abstract":"We present a translation from linear temporal logic with past to\u0000deterministic Rabin automata. The translation is direct in the sense that it\u0000does not rely on intermediate non-deterministic automata, and asymptotically\u0000optimal, resulting in Rabin automata of doubly exponential size. It is based on\u0000two main notions. One is that it is possible to encode the history contained in\u0000the prefix of a word, as relevant for the formula under consideration, by\u0000performing simple rewrites of the formula itself. As a consequence, a formula\u0000involving past operators can (through such rewrites, which involve alternating\u0000between weak and strong versions of past operators in the formula's syntax\u0000tree) be correctly evaluated at an arbitrary point in the future without\u0000requiring backtracking through the word. The other is that this allows us to\u0000generalize to linear temporal logic with past the result that the language of a\u0000pure-future formula can be decomposed into a Boolean combination of simpler\u0000languages, for which deterministic automata with simple acceptance conditions\u0000are easily constructed.","PeriodicalId":501124,"journal":{"name":"arXiv - CS - Formal Languages and Automata Theory","volume":"49 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140839358","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"FSM Builder: A Tool for Writing Autograded Finite Automata Questions","authors":"Eliot Wong Robson, Sam Ruggerio, Jeff Erickson","doi":"arxiv-2405.01717","DOIUrl":"https://doi.org/arxiv-2405.01717","url":null,"abstract":"Deterministic and nondeterministic finite automata (DFAs and NFAs) are\u0000abstract models of computation commonly taught in introductory computing theory\u0000courses. These models have important applications (such as fast regular\u0000expression matching), and are used to introduce formal language theory.\u0000Undergraduate students often struggle with understanding these models at first,\u0000due to the level of abstraction. As a result, various pedagogical tools have\u0000been developed to allow students to practice with these models. We introduce\u0000the FSM Builder, a new pedagogical tool enabling students to practice\u0000constructing DFAs and NFAs with a graphical editor, giving personalized\u0000feedback and partial credit. The algorithms used for generating these are\u0000heavily inspired by previous works. The key advantages to its competitors are\u0000greater flexibility and scalability. This is because the FSM Builder is\u0000implemented using efficient algorithms from an open source package, allowing\u0000for easy extension and question creation. We discuss the implementation of the\u0000tool, how it stands out from previous tools, and takeaways from experiences of\u0000using the tool in multiple large courses. Survey results indicate the interface\u0000and feedback provided by the tool were useful to students.","PeriodicalId":501124,"journal":{"name":"arXiv - CS - Formal Languages and Automata Theory","volume":"30 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140881775","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Finding Diverse Strings and Longest Common Subsequences in a Graph","authors":"Yuto Shida, Giulia Punzi, Yasuaki Kobayashi, Takeaki Uno, Hiroki Arimura","doi":"arxiv-2405.00131","DOIUrl":"https://doi.org/arxiv-2405.00131","url":null,"abstract":"In this paper, we study for the first time the Diverse Longest Common\u0000Subsequences (LCSs) problem under Hamming distance. Given a set of a constant\u0000number of input strings, the problem asks to decide if there exists some subset\u0000$mathcal X$ of $K$ longest common subsequences whose diversity is no less than\u0000a specified threshold $Delta$, where we consider two types of diversities of a\u0000set $mathcal X$ of strings of equal length: the Sum diversity and the Min\u0000diversity defined as the sum and the minimum of the pairwise Hamming distance\u0000between any two strings in $mathcal X$, respectively. We analyze the\u0000computational complexity of the respective problems with Sum- and Min-diversity\u0000measures, called the Max-Sum and Max-Min Diverse LCSs, respectively,\u0000considering both approximation algorithms and parameterized complexity. Our\u0000results are summarized as follows. When $K$ is bounded, both problems are\u0000polynomial time solvable. In contrast, when $K$ is unbounded, both problems\u0000become NP-hard, while Max-Sum Diverse LCSs problem admits a PTAS. Furthermore,\u0000we analyze the parameterized complexity of both problems with combinations of\u0000parameters $K$ and $r$, where $r$ is the length of the candidate strings to be\u0000selected. Importantly, all positive results above are proven in a more general\u0000setting, where an input is an edge-labeled directed acyclic graph (DAG) that\u0000succinctly represents a set of strings of the same length. Negative results are\u0000proven in the setting where an input is explicitly given as a set of strings.\u0000The latter results are equipped with an encoding such a set as the longest\u0000common subsequences of a specific input string set.","PeriodicalId":501124,"journal":{"name":"arXiv - CS - Formal Languages and Automata Theory","volume":"14 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140839542","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}