Formal Aspects of Computing最新文献

{"title":"Mechanised Operational Reasoning for C11 Programs with Relaxed Dependencies","authors":"Daniel Wright, Sadegh Dalvandi, Mark Batty, Brijesh Dongol","doi":"10.1145/3580285","DOIUrl":"https://doi.org/10.1145/3580285","url":null,"abstract":"Verification techniques for C11 programs have advanced significantly in recent years with the development of operational semantics and associated logics for increasingly large fragments of C11. However, these semantics and logics have been developed in a restricted setting to avoid the thin-air-read problem. In this article, we propose an operational semantics that leverages an intra-thread partial order (called semantic dependencies) induced by a recently developed denotational event-structure-based semantics. We prove that our operational semantics is sound and complete with respect to the denotational semantics. We present an associated logic that generalises a recent Owicki–Gries framework for RC11 RAR (repaired C11) with relaxed and release-acquire accesses. We describe the mechanisation of the logic in the Isabelle/HOL theorem prover, which we use to prove correctness of a number of examples.","PeriodicalId":50432,"journal":{"name":"Formal Aspects of Computing","volume":"35 1","pages":"1 - 27"},"PeriodicalIF":1.0,"publicationDate":"2023-01-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43201561","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A Refinement-based Formal Development of Cyber-physical Railway Signalling Systems","authors":"Yamine Aït-Ameur, Sergiy Bogomolov, Guillaume Dupont, Alexei Iliasov, Alexander Romanovsky, Paulius Stankaitis","doi":"https://dl.acm.org/doi/10.1145/3524052","DOIUrl":"https://doi.org/https://dl.acm.org/doi/10.1145/3524052","url":null,"abstract":"<p>For years, formal methods have been successfully applied in the railway domain to formally demonstrate safety of railway systems. Despite that, little has been done in the field of formal methods to address the cyber-physical nature of modern railway signalling systems. In this article, we present an approach for a formal development of cyber-physical railway signalling systems that is based on a refinement-based modelling and proof-based verification. Our approach utilises the Event-B formal specification language together with a hybrid system and communication modelling patterns to developing a generic hybrid railway signalling system model that can be further refined to capture a specific railway signalling system. The main technical contribution of this article is the refinement of the hybrid train Event-B model with other railway signalling sub-systems. The complete model of the cyber-physical railway signalling system was formally proved to ensure a safe rolling stock separation and prevent their derailment. Furthermore, the article demonstrates the advantage of the refinement-based development approach of cyber-physical systems, which enables a problem decomposition and in turn reduction in the verification and modelling effort.</p>","PeriodicalId":50432,"journal":{"name":"Formal Aspects of Computing","volume":"36 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2023-01-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138517771","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Compositional Verification of Railway Interlocking Systems","authors":"Anne Elisabeth Haxthausen, Alessandro Fantechi","doi":"https://dl.acm.org/doi/10.1145/3549736","DOIUrl":"https://doi.org/https://dl.acm.org/doi/10.1145/3549736","url":null,"abstract":"<p>Model checking techniques have often been applied to the verification of railway interlocking systems, responsible for guiding trains safely through a given railway network. However, these techniques fail to scale to the interlocking systems controlling large stations, composed of hundreds and even thousands of controlled entities, due to the state space explosion problem. Indeed, interlocking systems exhibit a certain degree of locality that allows some reasoning only on the mere set of entities that regard the train movements, but safe routing through a complex station layout requires a global reservation policy, which can require global state conditions to be taken into account.</p><p>In this article, we present a compositional approach aimed at chopping the verification of a large interlocking system into that of smaller fragments, exploiting in each fragment a proper abstraction of the global information on routing state. A proof is given of the thesis that verifying the safety of the smaller fragments is sufficient to verify the safety of the whole network. Experiments using this compositional approach have shown important gains in performance of the verification, as well as in the size of affordable station layouts.</p>","PeriodicalId":50432,"journal":{"name":"Formal Aspects of Computing","volume":"122 1","pages":""},"PeriodicalIF":1.0,"publicationDate":"2023-01-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138517762","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Review of Logical Analysis of Hybrid Systems","authors":"Gabriele Paveri-Fontana","doi":"10.1145/3561612","DOIUrl":"https://doi.org/10.1145/3561612","url":null,"abstract":"The book is an extensive presentation of deductive methods for hybrid systems’ verification rooted in dynamic logic. The author develops both formal specification languages for hybrid systems and automated verification techniques based on them. The main focus is on the theoretical aspects of the approach, but implementation issues are also widely addressed, and a functioning tool is presented at the end of the book. The book, which is now a few years old, is based on the Ph.D. thesis of the author, but is still current, especially the more theoretical parts, as it provides the foundations, for example, of the approach of Reference [3]. Given its origin, the book is certainly of great interest for researchers dealing with hybrid systems, but it is also recommendable for anyone who is interested in the general topics of modeling and verification of complex (timed) systems. A good degree of familiarity with formal methods and mathematical logic is necessary to fully appreciate the contents of the book. The book is divided into three parts, plus an appendix. Part I focuses on theoretical aspects. The book’s approach stems from the necessity of","PeriodicalId":50432,"journal":{"name":"Formal Aspects of Computing","volume":" ","pages":"1 - 2"},"PeriodicalIF":1.0,"publicationDate":"2022-12-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49563207","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A Deep Reinforcement Learning Framework with Formal Verification","authors":"Zakaryae Boudi, Abderrahim Ait Wakrime, Mohamed Toub, M. Haloua","doi":"10.1145/3577204","DOIUrl":"https://doi.org/10.1145/3577204","url":null,"abstract":"Artificial Intelligence (AI) and data are reshaping organizations and businesses. Human Resources (HR) management and talent development make no exception, as they tend to involve more automation and growing quantities of data. Because this brings implications on workforce, career transparency, and equal opportunities, overseeing what fuels AI and analytical models, their quality standards, integrity, and correctness becomes an imperative for those aspiring to such systems. Based on an ontology transformation to B-machines, this article presents an approach to constructing a valid and error-free career agent with Deep Reinforcement Learning (DRL). In short, the agent's policy is built on a framework we called Multi State-Actor (MuStAc) using a decentralized training approach. Its purpose is to predict both relevant and valid career steps to employees, based on their profiles and company pathways (observations). Observations can comprise various data elements such as the current occupation, past experiences, performance, skills, qualifications, and so on. The policy takes in all these observations and outputs the next recommended career step, in an environment set as the combination of an HR ontology and an Event-B model, which generates action spaces with respect to formal properties. The Event-B model and formal properties are derived using OWL to B transformation.","PeriodicalId":50432,"journal":{"name":"Formal Aspects of Computing","volume":"35 1","pages":"1 - 17"},"PeriodicalIF":1.0,"publicationDate":"2022-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47542056","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Compositional Reasoning for Non-multicopy Atomic Architectures","authors":"Nicholas Coughlin, Kirsten Winter, Graeme Smith","doi":"10.1145/3574137","DOIUrl":"https://doi.org/10.1145/3574137","url":null,"abstract":"Rely/guarantee reasoning provides a compositional approach to reasoning about concurrent programs. However, such reasoning traditionally assumes a sequentially consistent memory model and hence is unsound on modern hardware in the presence of data races. In this article, we present a rely/guarantee-based approach for non-multicopy atomic weak memory models, i.e., where a thread’s stores are not simultaneously propagated to all other threads and hence are not observable by other threads at the same time. Such memory models include those of the earlier versions of the ARM processor as well as the POWER processor. This article builds on our approach to compositional reasoning for multicopy atomic architectures, i.e., where a thread’s stores are simultaneously propagated to all other threads. In that context, an operational semantics can be based on thread-local instruction reordering. We exploit this to provide an efficient compositional proof technique in which weak memory behaviour can be shown to preserve rely/guarantee reasoning on a sequentially consistent memory model. To achieve this, we introduce a side-condition, reordering interference freedom on each thread, reducing the complexity of weak memory to checks over pairs of reorderable instructions. In this article, we extend our approach to non-multicopy atomic weak memory models. We utilise the idea of reordering interference freedom between parallel components. This by itself would break compositionality but serves as a vehicle to derive a refined compatibility check between rely and guarantee conditions, which takes into account the effects of propagations of stores that are only partial, i.e., not covering all threads. All aspects of our approach have been encoded and proved sound in Isabelle/HOL.","PeriodicalId":50432,"journal":{"name":"Formal Aspects of Computing","volume":"35 1","pages":"1 - 30"},"PeriodicalIF":1.0,"publicationDate":"2022-12-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46436005","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"From Non-punctuality to Non-adjacency: A Quest for Decidability of Timed Temporal Logics with Quantifiers","authors":"S. Krishna, Khushraj Madnani, Manuel Mazo Jr., P. Pandya","doi":"10.1145/3571749","DOIUrl":"https://doi.org/10.1145/3571749","url":null,"abstract":"Metric Temporal Logic (MTL) and Timed Propositional Temporal Logic (TPTL) are prominent real-time extensions of Linear Temporal Logic (LTL). In general, the satisfiability checking problem for these extensions is undecidable when both the future (Until, U) and the past (Since, S) modalities are used (denoted by MTL[U,S] and TPTL[U,S]). In a classical result, the satisfiability checking for Metric Interval Temporal Logic (MITL[U,S]), a non-punctual fragment of MTL[U,S], is shown to be decidable with EXPSPACE complete complexity. A straightforward adoption of non-punctuality does not recover decidability in the case of TPTL[U,S]. Hence, we propose a more refined notion called non-adjacency for TPTL[U,S] and focus on its 1-variable fragment, 1-TPTL[U,S]. We show that non-adjacent 1-TPTL[U,S] is strictly more expressive than MITL. As one of our main results, we show that the satisfiability checking problem for non-adjacent 1-TPTL[U,S] is decidable with EXPSPACE complete complexity. Our decidability proof relies on a novel technique of anchored interval word abstraction and its reduction to a non-adjacent version of the newly proposed logic called PnEMTL. We further propose an extension of MSO [<] (Monadic Second Order Logic of Orders) with Guarded Metric Quantifiers (GQMSO) and show that it characterizes the expressiveness of PnEMTL. That apart, we introduce the notion of non-adjacency in the context of GQMSO (NA-GQMSO), which is a syntactic generalization of logic Q2MLO due to Hirshfeld and Rabinovich and show the decidability of satisfiability checking for NA-GQMSO.","PeriodicalId":50432,"journal":{"name":"Formal Aspects of Computing","volume":"35 1","pages":"1 - 50"},"PeriodicalIF":1.0,"publicationDate":"2022-12-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45709905","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Review of Understanding Programming Languages","authors":"A. Butterfield","doi":"10.1145/3569959","DOIUrl":"https://doi.org/10.1145/3569959","url":null,"abstract":"First, a disclosure: I had every intention of buying this book before being offered the chance to review it. This was due mainly to the fact that my introduction to formal methods was via a previous book by the same author [1]! This book shows how formal specifications and semantics can enhance the quality of program and specification language development by clarifying key concepts early, and providing a clear basis for assessing the correctness of their implementations. The material in this book has also been used in final-year undergraduate teaching for a decade. This book is much more than a textbook, however. It mixes complete technical examples with commentary and copious historical notes about the development of programming languages, and their on/off relationship with formal techniques. This commentary makes the book a very natural and fluid read, and worth dipping into, as well as reading in order. Another key feature of the book is the introduction and discussion of various “Challenges” and “Language Issues.” There are 8 of the former, and 46 of the latter. These help to distill out key aspects and concerns. The book starts by showing how the ideas develop for “typical” (i.e., imperative) programming languages. This starts by using VDM notation to specify a structured operational semantics for a simple untyped imperative language. It then adds more features such as types, and code blocks. A key theme of this book is how the very definition of the semantic objects determines what the (dynamic) semantic possibilities will be. For example, dealing with memory locations, the choice to make them uninterpreted tokens rather than numbers, means that address arithmetic is ruled out. This is a significant semantic modelling choice. The remainder of the book starts to look at more complex language features, such as object orientation, records, pointers, functions/procedures, and concurrency leading to a semantics for a concurrent object-oriented language. Chapter 8 looks at shared variable concurrency and all its challenges. It shows how small-step operation semantics is able to model the non-deterministic interleaving behaviour. It then turns its attention to proof techniques, ranging from Rely/Guarantee, to Concurrent Separation Logic, and very recent mixings of the two. The author also makes the point that any process algebra that can model state change has to deal with the issue of interference: this includes CCS, CSP, and many others. Chapter 9 builds on Chapter 8 to combine concurrency with OO, in the form of the COOL language. As already mentioned above, just describing the semantic objects suffices to define the","PeriodicalId":50432,"journal":{"name":"Formal Aspects of Computing","volume":" ","pages":"1 - 2"},"PeriodicalIF":1.0,"publicationDate":"2022-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47193248","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Review on Theories of Programming: The Life and Works of Tony Hoare","authors":"Jonathan P. Bowen","doi":"10.1145/3560267","DOIUrl":"https://doi.org/10.1145/3560267","url":null,"abstract":"Sir Tony Hoare FRS is one of the leading computer scientists in the world. This book celebrates Hoare’s life and work as the 1980 winner of the ACM A. M. Turing Award [3], widely considered to be the nearest equivalent to the Nobel Prize in computer science. The Association for Computing Machinery (ACM) has decided to produce a series of books on Turing Award winners and this book forms part of that series. Tony Hoare’s contributions to computer science have been celebrated in previous books. The 1994 book A Classical Mind [4], referring to Hoare’s educational background in classics (“Literae Humaniores” at Oxford University), was produced as a collection of contributions by colleagues in celebration of Hoare’s 60th birthday. This was part of the Prentice Hall International Series in Computer Science, a series founded by Hoare and then edited by him for many years. In 1999, a Symposium was held in Oxford to celebrate Tony Hoare’s official “retirement” from the Oxford University Computing Laboratory and the Programming Research Group (PRG) there, although he continued to work for many further years at Microsoft Research in Cambridge. Several other Turing Award winners contributed to the Symposium and its associated proceedings Millennial Perspectives in Computer Science [2]. In 2006, the Computer History Museum, based in California, USA, celebrated Tony Hoare’s life with an oral history interview held in Cambridge [1], later summarized in the Communications of the ACM [5]. The book under review continues the celebration of Tony Hoare’s life and work. As in the previous books mentioned above, the volume mainly consists of contributions by Hoare’s colleagues, but also includes selected contributions by Hoare himself. The appendices provide additional relevant material. The volume is divided into seven parts. Part I provided introductory material including Hoare’s 1980 Turing Award lecture, originally published in the Communications of the ACM, together with an overview of Hoare’s ideas by the book’s editors. Part II covers program verification, a major aspect of Hoare’s contribution to computer science. Part III includes two chapters in Communicating Sequential Processes (CSP), a seminal approach to modelling concurrency formally using a process algebra. Part IV covers Hoare’s approach to teaching and his links with industry. Although Hoare has been a major contributor to theory underlying computer science, he has always recognized the importance of linking this with practical application. Part V presents","PeriodicalId":50432,"journal":{"name":"Formal Aspects of Computing","volume":"34 1","pages":"1 - 3"},"PeriodicalIF":1.0,"publicationDate":"2022-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43037475","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The Chemical Ecology of Benzoxazinoids.","authors":"Christelle Aurélie Maud Robert, Pierre Mateo","doi":"10.2533/chimia.2022.928","DOIUrl":"10.2533/chimia.2022.928","url":null,"abstract":"<p><p>Benzoxazinoids are specialized metabolites that modulate plant physiology and plant interactions with their environment. In this review, we synthesize their multiple functions and ecological relevance. We first provide an overview of benzoxazinoid biosynthesis and highlight known regulatory elements involved in modulating their production. We then outline the role of benzoxazinoids in plant nutrition, vegetative and reproductive growth, and defense. We further summarize benzoxazinoid response to environmental factors such as temperature, drought, CO2, light, or nutrient levels and emphasize their potential role in tolerating abiotic stresses. Finally, we argue that benzoxazinoids act as a strong selective force on different trophic levels by shaping the plant interactions with microbes, insect herbivores, and competitor plants. Understanding the pivotal role of benzoxazinoids in plant biology is crucial to apprehend their impact on (agro)ecosystem functioning and diversity.</p>","PeriodicalId":50432,"journal":{"name":"Formal Aspects of Computing","volume":"21 1","pages":"928-938"},"PeriodicalIF":1.2,"publicationDate":"2022-11-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73992148","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"计算机科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}