Showing papers in "The Journal of Logic and Algebraic Programming in 2021"

Abstract: Multiparty sessions are systems of concurrent processes, which allow several participants to communicate by sending and receiving messages. Their overall behaviour can be described by means of global types. Typable multiparty sessions enjoy lock-freedom. We look at multiparty sessions as open systems by allowing one to compose multiparty sessions by transforming two of their participants into a pair of coupled gateways, forwarding messages between the two sessions. Gateways need to be compatible. We show that the session resulting from the composition can be typed, and its type can be computed from the global types of the starting sessions. As a consequence, lock-freedom is preserved by composition. Compatibility between global types is necessary, since systems obtained by composing sessions with incompatible global types have locks (or they are not sessions). We also define direct composition, which allows one to connect two global types without using gateways. Finally, we propose a decomposition operator, to split a global type into two, which is the left inverse of direct composition. Direct composition and decomposition on global types prepare the ground for a novel framework allowing for the modular design and implementation of distributed systems.

Abstract: This study aimed to analyze the students' interlingual and intralingual interferences of Tourism Study Program at a State University in North Bali. A qualitative approach was applied by examining the students' final projects of English writing for the academic year 2020/2021. In this case study, 15 final projects were chosen using the purposive sampling technique. Data collection was done through reading, note-taking, classifying, and describing. The findings revealed that the most frequent interlingual form produced by the students was using Indonesian Syntax Pattern, while the intralingual form was the simplifications. Therefore, interlingual and intralingual interferences were found in the students' final project. There are two implications of this study, i.e. (i) teachers need to enhance their pedagogy for the teaching and learning sessions, particularly English grammar, (ii) students should learn more the English grammatical rules, which they can access many sources to learn English through watching a movie, listening to songs, talking with native speakers, reading novels and magazines. Abstrak : Penelitian ini bertujuan untuk menganalisis interlingual dan intralingual mahasiswa Program Studi Pariwisata di salah satu Universitas Negeri di Bali Utara. Pendekatan kualitatif digunakan dalam penelitian ini dengan menguji tugas akhir siswa dalam penulisan bahasa Inggris pada tahun ajaran 2020/2021. Dalam studi kasus ini, dipilih 15 tugas akhir dengan teknik purposive sampling. Pengumpulan data dilakukan melalui membaca, mencatat, mengklasifikasi, dan mendeskripsikan. Hasil temuan mengungkapkan bentuk interlingual yang paling sering dihasilkan oleh siswa adalah menggunakan Pola Sintaks Bahasa Indonesia sedangkan bentuk intralingualnya adalah penyederhanaan. Dengan dimikian, terdapat error interlingual dan intralingual dalam tugas akhir mahasiswa. Ada dua implikasi dari penelitian ini, yaitu (i) pengajar perlu meningkatkan pedagogi mereka untuk proses belajar mengajar khususnya tata bahasa Inggris, (ii) pembelajar harus mempelajari lebih lanjut aturan tata bahasa Inggris. Mereka dapat mengakses banyak sumber untuk belajar bahasa Inggris seperti menonton film, mendengarkan lagu, berbicara dengan penutur asli, membaca novel maupun majalah.

Abstract: The BPMN standard has a huge uptake in modelling business processes within the same organisation or collaborations involving multiple interacting participants. It is widely accepted by the Business Process Management community that a solid formal framework for the notation can help designers to properly understand their BPMN models as well as to state and verify model properties. With this aim in mind, we provide a formal characterisation of BPMN collaborations and some of the most significant correctness properties in the business process domain; namely, well-structuredness, safeness and soundness. We exploit this formalisation to classify BPMN models according to the properties they satisfy and their compositionality, resulting in a systematic study that gives evidence of expected results, closes conjectures and provides novel results. An experimentation to assess the impact of the considered properties on the practice of modelling is carried out on the BPMN models available in a public and populated repository.

Abstract: We present a new algorithm for determining the satisfiability of conjunctions of non-linear polynomial constraints over the reals, which can be used as a theory solver for satisfiability modulo theory (SMT) solving for non-linear real arithmetic. The algorithm is a variant of Cylindrical Algebraic Decomposition (CAD) adapted for satisfiability, where solution candidates (sample points) are constructed incrementally, either until a satisfying sample is found or sufficient samples have been sampled to conclude unsatisfiability. The choice of samples is guided by the input constraints and previous conflicts. The key idea behind our new approach is to start with a partial sample; demonstrate that it cannot be extended to a full sample; and from the reasons for that rule out a larger space around the partial sample, which build up incrementally into a cylindrical algebraic covering of the space. There are similarities with the incremental variant of CAD, the NLSAT method of Jovanovic and de Moura, and the NuCAD algorithm of Brown; but we present worked examples and experimental results on a preliminary implementation to demonstrate the differences to these, and the benefits of the new approach.

Abstract: Using multisets, we develop novel techniques for mechanizing the proofs of the synthesis conjectures for list–sorting algorithms, and we demonstrate them in the Theorema system. We use the classical principle of extracting the algorithm as a set of rewrite rules based on the witnesses found in the proof of the synthesis conjecture produced from the specification of the desired function (input and output conditions). The proofs are in natural style, using standard rules, but most importantly domain specific inference rules and strategies. In particular the use of multisets allows us to develop powerful strategies for the synthesis of arbitrarily structured recursive algorithms by general Noetherian induction, as well as for the automatic generation of the specifications of all necessary auxiliary functions (insert, merge, split), whose synthesis is performed using the same method. The proof techniques are implemented in the Theorema system and generate 8 sorting algorithms and 19 auxiliary functions.

Abstract: We present a system of session types based on adjoint logic which generalizes standard binary session types. Our system allows us to uniformly capture several new behaviors in the space of asynchronous message-passing communication, including multicast, where a process sends a single message to multiple clients, replicable services, which have multiple clients and replicate themselves on-demand to handle requests from those clients, and cancellation, where a process discards a channel without communicating along it. We provide session fidelity and deadlock-freedom results for this system, from which we then derive a logically justified form of garbage collection.

Abstract: Context-sensitive rewriting is a restriction of term rewriting which is obtained by imposing replacement restrictions on the arguments of function symbols. It has proven useful to analyze computational properties of programs written in sophisticated rewriting-based programming languages such as CafeOBJ , Haskell , Maude , OBJ *, etc. Also, a number of extensions (e.g., to conditional rewriting or constrained equational systems) and generalizations (e.g., controlled rewriting or forbidden patterns) of context-sensitive rewriting have been proposed. In this paper, we provide an overview of these applications and related issues.

Abstract: We propose an automated method for computing inductive invariants used to proving deadlock freedom of parametric component-based systems. The method generalizes the approach for computing structural trap invariants from bounded to parametric systems with general architectures. It symbolically extracts trap invariants from interaction formulae defining the system architecture. The paper presents the theoretical foundations of the method and proves its soundness. It also reports on a preliminary experimental evaluation on several textbook examples.

Abstract: Thematic learning requires teachers' creativity in selecting and developing learning media; one of them is by using professional flip pdf learning media. This study aimed to determine the feasibility and investigate teachers' and students' responses towards professional flip pdf for thematic learning with the 'loving plants and animals' theme. This research used Research and Development method with Borg and Gall model. The data collecting procedures were through observation, interview, and documentation. The results indicated that The development of learning media professional flip pdf gained 94.54% from media experts with the very feasible category, material experts 86.66% with the very feasible category, and linguists 94.54% with a very feasible category. In addition, the average of teachers' response obtained was 95% with the very feasible category. The small-scale trial was 91.3%, and the large-scale trial was obtained 95.8%, both with very attractive interpretation criteria. Therefore, professional pdf flip-based learning media are very feasible and very interesting to be used as thematic learning media. Abstrak: Pembelajaran tematik membutuhkan kreativitas guru dalam memilih dan mengembangkan media pembelajaran; salah satunya dengan menggunakan media pembelajaran flip pdf professional. Penelitian ini bertujuan untuk mengetahui kelayakan, respon guru dan siswa terhadap flip pdf profesional untuk pembelajaran tematik dengan tema 'menyayangi tumbuhan dan binatang'. Penelitian ini menggunakan metode Research and Development dengan model Borg and Gall. Teknik pengumpulan data dalam penelitian menggunakan observasi, wawancara, angket dan dokumentasi. Hasil penelitian menunjukkan bahwa pengembangan media pembelajaran flip pdf profesional diperoleh rata-rata 94,54% dari ahli media dengan kategori sangat layak, ahli materi 86,66% dengan kategori sangat layak, dan ahli bahasa 94,54% dengan kategori sangat layak. Selain itu, rata-rata respon guru yang diperoleh adalah 95% dengan kategori sangat layak. Uji coba skala kecil sebesar 91,3% dan uji coba skala besar diperoleh 95,8%, keduanya mendapat kriteria interpretasi sangat menarik. Denga demikian, media pembelajaran berbasis flip pdf profesional sangat layak dan sangat menarik untuk digunakan sebagai media pembelajaran tematik.

Abstract: Graphs play an important role in many areas of Computer Science. In particular, our work is motivated by model-driven software development and by graph databases. For this reason, it is very important to have the means to express and to reason about the properties that a given graph may satisfy. With this aim, in this paper we present a visual logic that allows us to describe graph properties, including navigational properties, i.e., properties about the paths in a graph. The logic is equipped with a deductive tableau method that we have proved to be sound and complete.

Abstract: We revise soft constraint automata, wherein transitions are weighted and each action has an associated preference value. We first relax the underlying algebraic structure to allow bipolar preferences. We then equip automata with memory locations, that is, with an internal state to remember and update information from transition to transition. We furthermore revise automata operators, such as composition and hiding, providing examples on how such memory locations interact with preferences. We finally apply our framework to encode context-sensitive behaviour.

Abstract: This study examines the impact of fake news discourse on perceptions of news media credibility. If participants are told they have been exposed to fake news, does this lead them to trust information institutions less, including the news media? Study 1 (n = 188) found that news media credibility decreased when participants were told they saw fake news, while news credibility did not change when participants were told they saw real news. Study 2 (n = 400) found that those who saw fake news – and were told they saw a fake news post – decreased their trust in the news media while those who saw fake news and were not debriefed did not change their perceptions of the news media. This shows that the social impact of fake news is not limited to its direct consequences of misinforming individuals, but also includes the potentially adverse effects of discussing fake news.

Abstract: Monitors in Runtime Verification are often constructed as black boxes: they provide verdicts on whether a property is satisfied or violated by the executing system under scrutiny, without much explanation as to why this is the case. In the best of cases, monitors might also return the trace observed, still leaving it up to the user to figure out the logic employed to reach the declared verdict from this trace. In this paper, we propose a local proof system for Linear Temporal Logic—a popular logic used in Runtime Verification—formalising the symbolic deductions within the constraints of Runtime Verification. We prove novel soundness and partial completeness results for this proof system with respect to the original semantics of the logic. Crucially, we show how such a deductive system can be used as a realistic basis for constructing online runtime monitors that provide explanations for their verdicts; we also show the resulting monitor algorithms to satisfy pleasing correctness criteria identified by other works, such as the decidability and incrementality of the analysis and the irrevocability of verdicts. Finally, we relate the expressiveness of the Linear Temporal Logic proof system to existing symbolic analysis techniques used in Runtime Verification.

Abstract: : This study aims to answer two crucial problems in education, especially school refusal for Madrasah Ibtidaiyah students. First, to express the students' reasons why they do school refusal. The second is to reveal the implications for the students' psychological and academic factors. In this study, the researcher used a descriptive qualitative approach to describe natural phenomena or human manipulation phenomena. The data was obtained through an interview with the seven students of Madrasah Ibtidaiyah Negeri 1 Semarang. To analyze the data, the researcher used non-statistical methods with interactive methods developed by Miles and Huberman. This research indicated that the students refuse to go to school because of physical conditions such as getting a fever or sick and psychological conditions such as not doing the homework and being bullied. The absence of the students during the learning process, especially Mathematics, affects their academic achievement. Abstrak: Penelitian ini bertujuan untuk menjawab dua masalah krusial dalam dunia pendidikan, khususnya school refusal pada siswa Madrasah Ibtidaiyah. Pertama, untuk mengungkapkan alasan siswa melakukan penolakan sekolah. Kedua, untuk mengungkap implikasi faktor psikologis dan akademis siswa. Dalam penelitian ini peneliti menggunakan pendekatan kualitatif deskriptif untuk mendeskripsikan fenomena yang ada, baik fenomena alam maupun manipulasi manusia. Data diperoleh melalui wawancara kepada tujuh siswa Madrasah Ibtidaiyah Negeri 1 Semarang. Untuk menganalisis data, peneliti menggunakan metode non statistik dengan metode interaktif yang dikembangkan oleh Miles dan Huberman. Hasil penelitian menunjukkan bahwa siswa menolak bersekolah karena kondisi fisik seperti demam atau sakit dan kondisi psikologis seperti tidak mengerjakan PR dan di-bully. Ketidakhadiran siswa selama proses pembelajaran khususnya pelajaran Matematika mempengaruhi prestasi akademiknya.

Abstract: Abstra ct : Religious plurality must be interpreted as plurality and multireligiousism in the nation's life and state. This research aimed to investigate Christian students' perception and motivation to study at Muhammadiyah University in Palopo. It was qualitative research with a phenomenological approach, which was conducted at Muhammadiyah University of Palopo. Five non-Muslim students were selected based on the purposive sampling technique, and the researchers became the main instruments. Other supporting instruments were interview guidelines, observation sheets, and tape recorders. The data collection techniques used are observation, in-depth interview, and documentation. The researchers made data reduction, data display, and drawing conclusions or verification in analyzing the data. The findings obtained revealed that Christian students' perception and motivation in enrolling Muhammadiyah University of Palopo was majorly affected by the support of parents, families, self-motivation, and their major at Muhammadiyah University of Palopo. Abstra k : Pluralitas agama merupakan suatu hal yang harus dimaknai sebagai kemajemukan dan multireligius dalam kehidupan berbangsa dan bernegara. Penelitian ini bertujuan untuk mengetahui persepsi dan motivasi mahasiswa Kristen dalam memilih Universitas Muhammadiyahdi Palopo. Pendekatan metode yang digunakan adalah kualitatif yang bercorak fenomenologi. Penelitian ini dilakukan di Universitas Muhammadiyah Palopo. Jumlah sampel yang digunakan yaitu 5 mahasiswa non muslim, dengan teknik pemilihan purposive sampling. Instrumen dalam penelitian ini yaitu peneliti itu sendiri sebagai instrumen utama, adapun instrument pendukung yaitu pedoman wawancara, lembar observasi, dan tape recorder. Teknik pengumpulan data yang digunakan yaitu observasi, wawancara mendalam (indepth interview), dan dokumentasi. Adapun analisis data yang digunakan yaitu reduksi data, displaydata dan pengambilan kesimpulan atau verifikasi. Hasil penelitian yang diperoleh bahwa Persepsi dan motivasi mahasiswa Kristen dalam memilih Universitas Muhammadiyah Palopo sebagian besar dipengaruhi oleh dukungan orang tua, keluarga, motivasi dalam diri, dan jurusan yang diinginkan ada di Universitas Muhammadiyah Palopo.

Abstract: Enhancing moral reasoning is the main goal of education in the perspective of cognitive-developmental theory. Strategies, approaches or learning methods are chosen based on the effectiveness in changing the level of moral reasoning of students from level of pre-conventional, to conventional and post-conventional. Dilemma Discussion Method has proven its effectiveness in increasing moral reasoning. Therefore, in order to be used in Akhlak learning (part of Pendidikan Agama Islam material) of the classroom, it is important to develop the steps of implementation (syntax) by using the principle of cognitive developmental theory. The results of this Research and Development (R & D) Design indicate that the product in the form of learning syntax from Dilemma Discussion Method is declared as valid with a mean score of 4.38 (greater than the criteria). Thus the product of development research in the form of a dilemma discussion method in learning Akhlaq is worth for being implemented. Abstrak: Peningkatan penalaran moral peserta didik merupakan tujuan utama pendidikan dalam perspektif teori cognitive-developmental. Strategi, pendekatan ataupun metode pembelajaran seharusnya dipilih berdasarkan keefektifannya dalam mengubah level penalaran moral peserta didik dari pre-conventional, menuju level conventional dan post-conventional. Metode diskusi dilema telah dibuktikan keefektifannya dalam meningkatkan penalaran moral. Oleh sebab itu, agar dapat digunakan dalam pembelajaran akhlak/moral (bagian dari mata pelajaran Pendidikan Agama Islam) di kelas, perlu diupayakan pengembangannya berupa langkah-langkah pelaksanaannya (sintak) metode tersebut dengan menggunakan prinsip-prinsip belajar cognitive developmental theory. Hasil penelitian pengembangan (Research & Development) ini menunjukkan bahwa produk berupa sintak pembelajaran dari metode diskusi dilemma dinyatakan valid karena telah memenuhi persyaratan validitas produk yakni mendapatkan skor rerata 4,38. Dengan demikian produk penelitian pengembangan berupa metode diskusi dilema dalam pembelajaran akhlaq layak untuk diimplementasikan.

Abstract: Matching logic was recently proposed as a unifying logic for specifying and reasoning about static structure and dynamic behavior of programs. In matching logic, patterns and specifications are used to uniformly represent mathematical domains (such as numbers and Boolean values), datatypes, and transition systems, whose properties can be reasoned about using one fixed matching logic proof system. In this paper we give a tutorial of matching logic. We use a suite of examples to explain the basic concepts of matching logic and show how to capture many important mathematical domains, datatypes, and transition systems using patterns and specifications. We put emphasis on the general principles of induction and coinduction in matching logic and show how to do inductive and coinductive reasoning about datatypes and codatatypes. To encourage the future tools development for matching logic, we propose and use throughout the paper a human-readable formal syntax to write specifications in a modular and compact way.

Abstract: In the perspective of Islamic education, the concept of liberalism and democracy in education is about owning academic freedom, in which a lecturer can teach, and the students have the right to learn without limitation and mixing it with irrational thoughts. This paper aims to elaborate on the nature and the development of liberalism and democracy in Islamic higher education from different sources. The type of research used in this study was library research. The data were taken from various books and articles related to the topic then analyzed using content analysis. Based on the findings, the theory of the Islamic education philosophy about the concept of liberalism and democracy were so sustainable to provide possible solutions in education management, educational facilities, and infrastructure. Also, it could be a solution for educators to implement teaching methods or approaches that are more suitable for the learning process. Abstrak: Dalam perspektif pendidikan Islam, konsep liberalisme dan demokrasi dalam pendidikan adalah tentang memiliki kebebasan akademik, dimana seorang dosen dapat mengajar, dan mahasiswa berhak untuk belajar tanpa batasan dan mencampurkannya dengan pemikiran-pemikiran yang irasional. Makalah ini bertujuan untuk mengelaborasi sifat dan perkembangan liberalisme dan demokrasi di perguruan tinggi Islam dari berbagai sumber. Jenis penelitian yang digunakan dalam penelitian ini adalah penelitian kepustakaan. Data diambil dari berbagai buku dan artikel yang berkaitan dengan topik tersebut kemudian dianalisis menggunakan analisis isi. Berdasarkan temuan tersebut, teori filosofi pendidikan Islam tentang konsep liberalisme dan demokrasi yang begitu lestari dapat memberikan solusi yang memungkinkan dalam pengelolaan pendidikan, sarana dan prasarana pendidikan. Selain itu, dapat menjadi solusi bagi pendidik untuk menerapkan metode atau pendekatan pengajaran yang lebih sesuai untuk proses pembelajaran.

Abstract: When verifying programs where the data have some recursive structure, it is natural to make use of global invariants that are themselves recursively defined. Though this is mathematically elegant, this makes the proofs more complex, as the preservation of these invariants now requires induction. In particular, this makes the proofs less amenable to automation. An alternative is to use local invariants attached to individual components of the structure and which only involve a bounded number of elements. We call these decentralized invariants. When the structure is updated, the footprint of the modification only impacts a bounded number of invariants and reestablishing them does not require induction. In this paper, we illustrate this idea on three non-trivial programs, for which we achieve fully automated proofs.

Abstract: Findel is a composable DSL for financial derivatives that can be executed on the blockchain. The language is simple and expressive enough to express complex derivatives. However, compared to its competitors, Findel does not guarantee that contracts progress properly. There is no default refund mechanism, and the economic enforcement is not handled by the language itself. Given the immutability of the blockchain, more caution should be taken in order to avoid undesired situations. In this paper, we address the formal verification of financial derivatives written in Findel. We define a formal semantics of Findel in Coq and we test it against the existing Findel test suite. We enrich our semantics with means to interactively formalise and prove properties about Findel contracts. The goal is to avoid mistakes in Findel contracts that may have a negative impact (e.g., stuck contract executions, money losses). The derived infrastructure is used to certify non-trivial contract examples that cover the most common types of derivatives (forwards/futures, swaps, options).

Abstract: We present a tool-supported approach for the model-driven testing of message-passing applications. Our approach envisages choreographies as a particularly suited model to derive tests in order to tame the problems of correctness of distributed applications.

Abstract: The timed synchronous dataflow graph model is a graphical model of computation that allows concurrency between processes This model is widely used due to its expressive power, semantic simplicity and predefined properties However, the lack of support for formal verification makes it difficult to manually verify user-defined properties, even for small-sized graphs This paper presents a formal verification solution of timed synchronous dataflow graphs based on the Lustre language and model checking The solution consists in an automatic translation of synchronous dataflow graphs into Lustre code and in coding the user-defined properties as Lustre expressions Use cases are presented showing the applicability of the method

Abstract: Software-Defined Networking (SDN) is a networking paradigm that has become increasingly popular in the last decade. The unprecedented control over the global behaviour of the network it provides opens a range of new opportunities for formal methods and much work has appeared in the last few years on providing bridges between SDN and verification. This article advances this research line and provides a link between SDN and traditional work on formal methods for verification of concurrent and distributed software—actor-based modelling. We show how SDN programs can be seamlessly modelled using actors, and thus existing advanced model checking techniques developed for actors can be directly applied to verify a range of properties of SDNs, including consistency of flow tables, violation of safety policies, and forwarding loops. Our model checker for SDNs is available through an online web interface, that also provides the SDN actor-models for a number of well-known SDN benchmarks.

Abstract: In this paper we study the solvability of the equality negation task in a simple wait-free model where two processes communicate by reading and writing shared variables or exchanging messages. In this task, the two processes start with a private input value in the set { 0 , 1 , 2 } , and after communicating, each one must decide a binary output value, so that the outputs of the processes are the same if and only if the input values of the processes are different. This task is already known to be unsolvable; our goal here is to prove this result using the dynamic epistemic logic (DEL) approach introduced by Goubault et al. (2018) [18] . We show that in fact, there is no epistemic logic formula that explains why the task is unsolvable. Furthermore, we observe that this task is a particular case of an epistemic covering task. We thus establish a connection between the existing DEL framework and the theory of covering spaces in topology, and prove that the same result holds for any epistemic covering task: no epistemic formula explains the unsolvability.

Abstract: The modal operators usually associated with the notions of possibility and necessity are classically duals This paper aims to defy that duality in a paraconsistent environment, namely in a Belnapian Hybrid logic where both propositional variables and accessibility relations are four-valued Hybrid logic, which is an extension of Modal logic, incorporates extra machinery such as nominals – for uniquely naming states – and a satisfaction operator – so that the formula under its scope is evaluated in the state whose name the satisfaction operator indicates In classical Hybrid logic the semantics of negation, when it appears before compound formulas, is carried towards subformulas, meaning that eventual inconsistencies can be found at the level of nominals or propositional variables but appear unrelated to the accessibility relations In this paper we allow inconsistencies in propositional variables and, by breaking the duality between modal operators, inconsistencies at the level of accessibility relations arise We introduce a sound and complete tableau system and a decision procedure to check if a formula is a consequence of a set of formulas Tableaux will be used to extract syntactic models for databases, which will then be compared using different inconsistency measures We conclude with a discussion about bisimulation

Abstract: Matrix interpretations are widely used in automated complexity analysis. Certifying such analyses boils down to determining the growth rate of A n for a fixed non-negative rational matrix A. There exists a conceptually simple algorithm to determine the growth rate, but this algorithm has the disadvantage that it is based on algebraic number computations. In this work we present an even simpler algorithm to compute the growth rate. Its soundness is based on a variant of a Perron–Frobenius theorem that has been conjectured in earlier work. So far it only has been proven for small matrices, and here we present a proof for the general case. We further verify both the algorithm and the new Perron–Frobenius theorem in the proof assistant Isabelle/HOL, and integrate it into CeTA , a verified certifier for various properties, including complexity proofs. Because of the new results, CeTA no longer requires a verified implementation of algebraic numbers.

Abstract: This work introduces a concept of explanations with respect to the violation of safe behaviours within software defined networks (SDNs) expressible in NetKAT. The latter is a network programming language based on a well-studied mathematical structure, namely, Kleene Algebra with Tests (KAT). Amongst others, the mathematical foundation of NetKAT gave rise to a sound and complete equational theory. In our setting, a safe behaviour is characterised by a NetKAT policy, or program, which does not enable forwarding packets from an ingress i to an undesirable egress e. We show how explanations for safety violations can be derived in an equational fashion, according to a modification of the existing NetKAT axiomatisation. We propose an approach based on the Maude system for actually computing the undesired behaviours witnessing the forwarding of packets from i to e as above. SDN-SafeCheck is a tool based on Maude equational theories satisfying important properties such as Church-Rosser and termination. SDN-SafeCheck automatically identifies all the undesired behaviours leading to e, covering forwarding paths up to a user specified size.

Abstract: The architecture of a system captures important design decisions for the system. Over time, changes in a system's implementation may lead to violations of specific design decisions. This problem is common in industry and known as architectural erosion. Since it may have severe consequences on the quality of a system, research has focused on the development of tools and techniques to address the presented problem. As of today, most of the approaches to detect architectural erosion employ static analysis techniques. While these techniques are well-suited for the analysis of static architectures, they reach their limit when it comes to dynamic architectures. Thus, in this paper, we propose an alternative approach based on runtime verification: We describe techniques to formally specify constraints for dynamic architectures and algorithms to translate such specifications to instrumentation code and corresponding monitors. The approach is implemented in Eclipse/EMF, demonstrated through a running example, and evaluated using two case studies.

Abstract: This study aims to observe the relationship between teacher professionalism and learning services, and students' learning outcomes at PAI Elementary School. Population of this study was all teachers and students while the samples were 21 teachers and 30 students. The data collection used observation, interview, and documentation. The data analysis technique used is a descriptive analysis using SPSS 11.5, factor analysis, and Rank Spearman correlation analysis. The results show that: first, there is no significant relationship between teacher professionalism and students’ learning outcomes of PAI Elementary School. This is due to the lack of professional human resources within the scope of PAI Elementary School. Second, the learning services for PAI Elementary School students are in the high category, and there is a significant relationship between learning services and learning outcomes of PAI Elementary School students, this is due to the excellent service provided to the students so that it has an impact on the students’ learning outcomes. Abstrak: Tujuan penelitian ini adalah untuk mengetahui hubungan profesionalisme guru dan layanan pendidikan terhadap hasil belajar siswa sekolah dasar. Populasi dalam penelitian ini adalah guru dan peserta didik sekolah dasar PAI dan sampel sebanyak 21 orang guru dan 30 orang peserta didik . Pengambilan data yang digunakan adalah observasi, wawancara, dan dokumentasi. Teknik analisis data yang digunakan adalah analisis deskriptif dengan menggunakan SPSS 11,5, analisis factor, analisis korelasi Rank Spearman. Hasil penelitian: Pertama, tidak terdapat hubungan yang signifikan antara profesionalisme Guru dengan hasil belajar siswa Sekolah Dasar PAI. Hal ini disebabkan kurangnya SDM yang professional dalam lingkup Sekolah Dasar PAI. Kedua, pelayanan pembelajaran pada siswa Sekolah Dasar PAI berada pada kategori tinggi, dan ada hubungan yang signifikan antara pelayanan pembelajaran dengan hasil belajar siswa Sekolah Dasar PAI, hal ini disebabkan karena Pelayanan prima yang diberikan oleh pihak sekolah kepada siswa sehingga berdampak terhadap hasil belajar siswa.

Abstract: To support Model Based Design of Cyber-Physical Systems (CPSs) many simulation based approaches to System Level Formal Verification (SLFV) have been devised. Basically, these are Bounded Model Checking approaches (since simulation horizon is of course bounded) relying on simulators to compute the system dynamics and thereby verify the given system properties. The main obstacle to simulation based SLFV is the large number of simulation scenarios to be considered and thus the huge amount of simulation time needed to complete the verification task. To save on computation time, simulation based SLFV approaches exploit the capability of simulators to save and restore simulation states. Essentially, such a time saving is obtained by optimising the simulation script defining the simulation activity needed to carry out the verification task. Although such approaches aim to (bounded) formal verification, as a matter of fact, the proof of correctness of the methods to optimise simulation scripts basically relies on an intuitive semantics for simulation scripting languages. This hampers the possibility of formally showing that the optimisations introduced to speed up the simulation activity do not actually omit checking of relevant behaviours for the system under verification. The aim of this paper is to fill the above gap by presenting an operational semantics for simulation scripting languages and by proving soundness and completeness properties for it. This, in turn, enables formal proofs of equivalence between unoptimised and optimised simulation scripts.