Verification (Computer Science)

Autonomous software agents are increasingly capable of modifying repositories, repairing tests, interpreting issue trackers, and proposing release candidates. This shift exposes a deployment-governance problem that conventional continuous integration and deployment pipelines do not solve: existing software supply-chain mechanisms can attest what artifact was built and signed, but they do not formally justify why a production deployment was authorized. This paper reframes deployment approval as a knowledge representation and reasoning problem. It proposes proof-carrying deployment, a framework in which a deployment is accepted only when the authorization decision can be represented as a machine-checkable certificate over explicit policy, canonical evidence, admissible inference rules, and independent validator attestations. The paper synthesizes ideas from software supply-chain security, policy logic, proofcarrying code, verifiable artificial intelligence, and distributed verification, and argues that the missing research object is decision-level provenance for autonomous deployment. A formal certificate model, research questions, theoretical properties, and an evaluation methodology are presented to position proofcarrying deployment as research agenda in trustworthy autonomous software systems.

Agentic AI systems are increasingly positioned as productivity infrastructure for cognitive work, yet they conflate scalable generation with productive completion, systematically transferring the burden of verification, contextual alignment, and operational reliability onto the human operator. This paper introduces the concept of Supervision Debt: the cumulative supervisory effort imposed on human operators by the asymmetric relationship between automated output generation and human-bounded validation. Drawing on recent empirical findings across legal practice, software development, and knowledge work, we demonstrate that this asymmetry produces a measurable productivity divergence in which efficiency gains attributed to automation are offset by rising verification burdens, metacognitive demand, and cognitive complacency. We argue that Supervision Debt reframes the central constraint of agentic AI from generative throughput to the human capacity required to render automated output reliable and actionable.

Günümüzün dijital araçlarındaki kullanım yoğunluğu ile birlikte bireyler daha fazla reklamlara maruz kalmaktadır. Reklam körlüğü sosyal medya platformlarında karşılaşılan özellikle video içerikli reklamlara duyarsız kalma veya bu reklamları sık sık atlama eylemidir. Bu çalışmada özellikle Z kuşağının sıklıkla kullanmış olduğu Tiktok ve Youtube platformlarında karşılaştıkları reklamlara yönelik reklam körlüğü algılamalarının analiz edilmesi amaçlanmıştır. Bu kapsamda bu platformları aktif olarak kullandığını belirten 113 üniversite öğrenci ile çevrimiçi anket uygulaması gerçekleştirilmiştir. Araştırma amacı doğrultusunda hazırlanan hipotezleri test etmek amacıyla Jamovi analiz programından yararlanılarak frekans analizleri, ki-kare testleri ve farklılık testleri gerçekleştirilmiştir. Yapılan analizler sonucunda cinsiyet, yaş, kullanılan platform türü ve kullanım süresi değişkenlerinin hiçbirinde reklam körlüğü puanları açısından istatistiksel olarak anlamlı bir farklılık bulunamamıştır. Çalışmada üniversite öğrencileri özelinde reklam körlüğünün mecradan ve süreden bağımsız olarak kronikleşen bir dijital alışkanlık olduğu sonucuna varılmıştır. Çalışma reklam verenlere yönelik sunulan önerilerle nihayete erdirilmiştir.

TLA + is a general purpose, formal specification language based on the Temporal Logic of Actions, with no built-in primitives for specifying real-time properties. Here, we use TLA + to define operators for specifying the temporal behavior of physical components obeying integral equations of evolution. These operators, together with previously defined operators for describing timing constraints, are used to specify a toy gas burner introduced by Ravn, Rischel, and Hansen. The burner is specified at three levels of abstraction, each of the two lower-level specifications implementing the next higher-level one. Correctness proofs are sketched.

AUTO DZ ACT is a verification-first, state-defined framework designed to evaluate scientific claims by explicitly comparing theoretical outputs and observational data under declared thresholds. The methodology enforces a strict separation between measurement, verification state, and interpretation, treating absence of data as a formal scientific outcome rather than an implicit assumption.

This work presents the journal-ready, editorially normalized application of AUTO DZ ACT v2.2 to the interstellar object 3I/ATLAS, relying exclusively on publicly accessible, authoritative datasets (MPC, NASA/JPL, ESA). Claims are classified into explicit epistemic states (0/0, DO/DZ, DZ, ∞/∞), ensuring reproducibility, traceability, and falsifiability.

The manuscript is archived authoritatively on Zenodo and is intended for journal submission, methodological scrutiny, and long-term reproducible reference.

Abstract Background and Objective: Modeling water quality of rivers can be used as one of the most effective tools for water quality management in rivers and reducing the environmental impacts of entering pollutants. The purpose of this paper is to use the valid QUAL2Kw 5.1 model to model water quality in Shahrood River. Method: In this paper, seven parameters of water quality have been used including dissolved oxygen (DO), biochemical demand oxygen (BOD), pH, total dissolved solids (TDS), total phosphorus, and total nitrogen four times in Shahrood River. Data from October of 2007 and July of 2008 were used to calibrate and data from September and October of 2008 were used to verify the model. Auto-calibration of model coefficients was done using genetic algorithm of the model. In order to compare simulated results with the observed data, determination coefficient and mean absolute error were used. Findings: The most important calibration coefficients of the model were related to TSS, BOD, total nitrogen and phosphorus. This model in simulation of pH and EC with mean absolute error of 0.19 and 163.89 during verification stage showed the most and the least accuracy, respectively. On average the minimum and maximum DO were measured 6.93 and 9.99 mg/L in September and October of 2008 respectively in Shahroud River. Also the highest and lowest accuracy of the model in simulating these parameters were related to July and October of 2008 with mean absolute error of 0.86 and 1.29, respectively. In addition the results showed accurate hydraulic modeling of hydraulic parameters changes of the river along the river had a great influence on modeling of the water river quality. Discussion and Conclusion: The results of this paper show the accuracy of the QUAL2Kw model in simulating water quality parameters of Shahrood River. On the other hand, the accuracy of the simulation of each parameter varies with the amount of its variation along the river so that the less the changes in a parameter along the river and at different intervals, the higher the accuracy of the model in simulating this parameter will be.

Signals coming out of human brain is considered as a new biometric. After acquisition, feature
extraction and classification of signals are done. To achieve this, spatial data/sensor fusion is done. EEG
features are classified using the neural network named as Elman neural network. 1600 raw EEG signals are
collected using maximum 35 informative channels and maximum recognition rate achieved is 98%. EEG
biometrics has got massive potential due to its sturdiness against any kind of scam.

Cloud computing is an emergent technology that has generated significant interest in the marketplace and is forecasted for high growth. Moreover, Cloud computing has a great impact on different type of users from individual consumers and businesses to small and medium size (SMBs) and enterprise businesses. Although there are many benefits to adopting Cloud computing, there are significant barriers to adoption, viz. security and privacy. In this paper, we focus on carefully planning security aspects regarding access control of Cloud computing solutions before implementing them and, furthermore, on ensuring they satisfy particular organizational security requirements. Specifically, we propose a methodology for the development of access control systems. The methodology is capable of utilizing existing security requirements engineering approaches for the definition and evaluation of access control models, and verification of access control systems against organizational security requirements using techniques that are based on formal methods. A proof of concept example is provided that demonstrates the application of the proposed methodology on Cloud computing systems.

The increased complexity of modern access control (AC) systems stems partly from the need to support diverse and multiple administrative domains. Systems engineering is a key technology to manage this complexity since it is capable of assuring that an operational system will adhere to the initial conceptual design and defined requirements. Specifically, the verification stage of an AC system should be based on techniques that have a sound and mathematical underpinning. Working on this assumption, model checking techniques are applied for the verification of predefined system properties, and thus, conducting a security analysis of a system. In this paper, we propose the utilization of automated and error-free model checking techniques for the verification of security properties in multidomain AC systems. Therefore, we propose a formal definition in temporal logic of four AC system properties regarding secure inter-operation with Role-Based Access Control (RBAC) policies in order to be verified by using model checking. For this purpose, we demonstrate the implementation of a tool chain for expressing RBAC security policies, reasoning on role hierarchies and properly feeding the model checking process. The proposed approach can be applied in any RBAC model to efficiently detect non-conformance between an AC system and its security specifications. As a proof of concept, we provide examples illustrating the verification of the defined secure inter-operation properties in multi-domain RBAC policies.

In this paper we consider Erdös-Mordell inequality and its extension in the plane of triangle to the Erdös-Mordell curve. Algebraic equation of this curve is derived, and using modern computer tools in mathematics, we verified one conjecture that relates to Erdös-Mordell curve.

: This report provides a summary of the research and related activities performed. The issue of trust is one of the most significant obstacles to broad use of autonomy technology by DoD and other agencies. The impact of this research supports creation of computational methods that create a bridge to engineering of trustworthy autonomous systems. Objectives of this research were (1) to operationalize the quality of benevolence and understand how it contributes to well-calibrated trust of, and reliance upon, autonomous systems, (2) to investigate portrayal of trust-related attributes in the humanmachine interface. Accomplishments include: (1) the formulation of benevolence as a complex belief structure with antecedent beliefs having semantic, temporal, causal and other interrelationships; (2) the mapping of a portion of this belief structure to measurable internal states of autonomous systems; (3) empirical evidence in support of the applicability of psychological concepts of interper...

There is a recognized need to employ autonomous agents in domains that are not amenable to conventional automation and/or which humans find difficult, dangerous, or undesirable to perform. These include time-critical and mission-critical applications in health, defense, transportation, and industry, where the consequences of failure can be catastrophic. A prerequisite for such applications is the establishment of wellcalibrated trust in autonomous agents. Our focus is specifically on human-machine trust in deployment and operations of autonomous agents, whether they are embodied in cyber-physical systems, robots, or exist only in the cyber-realm. The overall aim of our research is to investigate methods for autonomous agents to foster, manage, and maintain an appropriate trust relationship with human partners when engaged in joint, mutually interdependent activities. Our approach is grounded in a systems-level view of humans and autonomous agents as components in (one or more) encompassing metacognitive systems. Given human predisposition for social interaction, we look to the multi-disciplinary body of research on human interpersonal trust as a basis from which we specify engineering requirements for the interface between human and autonomous agents. If we make good progress in reverse engineering this "human social interface," it will be a significant step towards devising the algorithms and tests necessary for trustworthy and trustable autonomous agents. This paper introduces our program of research and reports on recent progress.

The area of software verification has grown its importance in software engineering. This is a bibliography of verification of a specialized class of softwares called compiler. The citations are sorted year wise in chronological order with most recent years first. The format of each citation is authors; Title; publisher; year. 2003

We present a method which accepts Interval Temporal Logic (ITL) formulas as specification and automatically generates state machines. The specification in ITL can also be used as a con- straint for a state machine which is an abstraction for an existing sequential circuit, which can be useful for redesign or engineering change. The generated state machines can be further pro-

Teamwork requires mutual trust among team members. Establishing and maintaining trust depends upon alignment of mental models, an aspect of shared awareness. We present a theory of how maintenance of model alignment is integral to fluid changes in relative control authority (i.e., adaptive autonomy) in human-robot teamwork.

This extended abstract takes advantage of a theory of software testing based on formal specifications to point out the benefits and limits of the use of formal methods to this end. A notion of exhaustive test set is defined according to the semantics of the formal notation, the considered conformance relation, and some testability hypotheses on the system under test. This gives a framework for the formalisation of test selection, test execution, and oracles, and, moreover, leads to the explicitation of those hypotheses underlying test selection strategies, such as uniformity hypotheses or regularity hypotheses. This explicitation provides some guides to complementary proofs, or tests, or instrumentations of the system under test. This approach has been applied to various formalisms: axiomatic specifications of data types, model-based specifications, process algebras, transition systems, etc. It provides some guiding principles for the development of testing methods given a formal specification notation and an associated conformance/refinement relation. It is at the origin of the development of some test environments based on SMT solvers and theorem provers.

Ontology is a conceptual model that is used to represent the concepts in a domain and relationship between the concepts. It can be used for sharing and reuse of knowledge that allows humans and machines to exchange diverse information. UML state machines used to describe the behavior of a software systems. This article aims at to provide a solution for representing UML state machine model as an ontology expressed in OWL. a method proposed is a conceptualization of UML state machine and its operation, in order to check its consistency and its conformity. we chose OWL to represent formally our state machine augmented with SWRL rules to represent the dynamic aspect of the operation system and SPARQL to query our ontology.

A compiler may be specified as a set of theorems, each describing how a construct in the programming language is translated into a sequence of machine instructions. The machine may be specified as an interpreter written in the programming language itself. Using refinement algebra, it can then be verified that interpreting a compiled program is the same or better than executing the original source program. The compiling specification is very similar to a logic program and thus a prototype compiler (and interpreter) may easily be produced in a language such as Prolog. A subset of the occarrl programming language and the transputer instruction set are used to illustrate the approach. An a~lvantage of the method is that new programming constructs can be added without necessarily affecting existing development work.

One of the common way or method to authenticate identity of person is biometric recognition system.With the growing employment of the iris recognition systems and associated research to support this, the need for large databases of iris images is growing. Iris is considered to be the most unique attribute possessed by an individual and is regarded as the most reliable form of biometric authentication. Iris portion of the eye image is complex annular part it contains many distinctive features such as arching ligaments, furrows and ridges. The compression algorithms developed for iris images have to preserve the details present in the iris part of the image, which are used for subsequent biometric processes. We propose here, a compression scheme of iris images using Mallat based wavelet transform using Directional Filter Bank. Mallat algorithm is based on the multiresolution, and it represents the wavelet transform as a pyramid. Directional Filter Bank provides the flexibility to obta...

We extend some properties of the fractal interpolation from the finite case to the case of countable set of data. The main result is that, given an countable system of data ∆ in [a, b] × Y , where [a, b] is a real interval and Y a compact metric space and ψ a proper continuous function which transforms ∆ in some other countable system of data, then ψ(A)

We propose in this paper an algebraic approach to hard-ware/software partitioning in Verilog Hardware Description Language (HDL). We explore a collection of algebraic laws for Verilog programs, from which we design a set of syntax-based algebraic rules to conduct hardware/software partitioning. The co-specification language and the target hardware and software description languages are specific subsets of Verilog. Through this, we confirm successful verification for the correctness of the partitioning process by an algebra of ...

In this paper, we are trying to introduce a method of selection of some web pages from a web application, which will be verified by using different validating mechanisms. The number of selected web pages cannot be higher than a previously established constant. The method of selection of these web pages must assure the highest possible quality of the verification of the entire application. The error detection of these web pages will automatically lead to the error detection in other pages. This fact will be realised by using an equivalence relation among the web pages of the web application.

This paper presents the development and design of a graphical user interface and a command line programming toolbox for construction, edition and observation of Interval Type-2 Fuzzy Inference Systems. The Interval Type-2 Fuzzy Logic System Toolbox (IT2FLS), is an environment for interval type-2 fuzzy logic inference system development. Tools that cover the different phases of the fuzzy system design process, from the initial description phase, to the final implementation phase, build the Toolbox. The Toolbox's best qualities are the capacity to develop complex systems and the flexibility that permits the user to extend the availability of functions for working with the use of type-2 fuzzy operators, linguistic variables, interval type-2 membership functions, defuzzification methods and the evaluation of Interval Type-2 Fuzzy Inference Systems.

Signals coming out of human brain is considered as a new biometric. After acquisition, feature extraction and classification of signals are done. To achieve this, spatial data/sensor fusion is done. EEG features are classified using the neural network named as Elman neural network. 1600 raw EEG signals are collected using maximum 35 informative channels and maximum recognition rate achieved is 98%. EEG biometrics has got massive potential due to its sturdiness against any kind of scam.

Öz: Gelişen teknoloji ile kullandığımız telefonlardan bilgisayarlara kadar kolaylıkla ulaşım sağlayabildiğimiz sosyal medya hayatlarımızda her geçen gün etkisini arttırmaktadır. Artan sosyal medya platformları ve bununla paralel olarak artış gösteren sosyal medya kullanıcılarının ulaştıkları ve paylaştıkları bilgilerin güvenirliği de tartışılır hale gelmiştir. Bu doğrultuda çalışmanın amacı, üniversite öğrencilerinin sosyal medya platformlarında üretilen paylaşımlara olan güven düzeylerinin ve bu paylaşımları teyit etme alışkanlıklarının tespit edilmesidir. Spor Bilimleri Fakültesi'nde öğrenim gören 177'si kadın 304'ü erkek toplam 481 öğrenci araştırmanın örneklemini oluşturmuştur. Veri toplama aracı olarak Çömlekçi ve Başol (2019) tarafından geliştirilen "Sosyal Medya Teyit/Güven Ölçeği" ve araştırmacılar tarafından oluşturulan kişisel bilgi formu kullanılmıştır. Katılımcılardan Google Form aracılığıyla toplanan verilerin demografik özelliklerini belirlemek amacıyla frekans ve yüzde analizi yapılmıştır. Ölçek puanlarının normal dağılım gösterip göstermediğini anlamak amacıyla basıklık (kurtosis) ve çarpıklık (skewness) analizi ve değişkenler arasındaki ilişkiyi belirlemek amacıyla t-testi ve ANOVA testleri yapılmıştır. Sonuçlar incelendiğinde, kadın katılımcıların erkek katılımcılara göre sosyal medyadan ulaştıkları bilgileri teyit etme alışkanlıklarının daha yüksek olduğu sonucuna ulaşılmıştır. Katılımcıların vermiş oldukları cevaplar neticesinde günlük sosyal medyada daha az vakit geçiren bireylerin sosyal medyaya daha az güven duydukları bulunmuştur. Çalışmaya katılanların büyük bir çoğunluğunun en sık kullandığı sosyal medya platformu Instagram'dır. Katılımcıların gelişmelerden haberdar olmak için internet haber siteleri yerine sosyal medya platformlarını tercih ettikleri sonucuna ulaşılmıştır.

This paper sketches a hard real-time programming language featuring operators for expressing timeliness requirements in an abstract, implementation-independent way and presents parts of the design and verification of a provably correct code generator for that language. The notion of implementation correctness used as an implicit specification of the code generator pays attention to timeliness requirements. Hence, formal verification of the code generator design is a guarantee of meeting all deadlines when executing generated code.

This paper sketches a hard real-time programming language featuring operators for expressing timeliness requirements in an abstract, implementation-independent way and presents parts of the design and verification of a provably correct code generator for that language. The notion of implementation correctness used as an implicit specification of the code generator pays attention to timeliness requirements. Hence, formal verification of the code generator design is a guarantee of meeting all deadlines when executing generated code.

In this paper, several improvements are proposed to previous work of automated classification of alcoholics and nonalcoholics. In the previous paper, multiplayer-perceptron neural network classifying energy of gamma band Visual Evoked Potential (VEP) signals gave the best classification performance using 800 VEP signals from 10 alcoholics and 10 non-alcoholics. Here, the dataset is extended to include 3560 VEP signals from 102 subjects: 62 alcoholics and 40 non-alcoholics. Three modifications are introduced to improve the classification performance: i) increasing the gamma band spectral range by increasing the pass-band width of the used filter ii) the use of Multiple Signal Classification algorithm to obtain the power of the dominant frequency in gamma band VEP signals as features and iii) the use of the simple but effective knearest neighbour classifier. To validate that these two modifications do give improved performance, a 10-fold cross validation classification (CVC) scheme is...

Current access control models have limitations in scenarios where digital objects are decomposed into smaller objects before sharing. We propose an access control model (digital object-based access model) for such scenarios involving object decomposition. Our model applies to the generic class of objects composing of documents, videos, and audio. We use temporal logic of actions to formally specify access policies in our model and verify different properties. Using mathematical modelling and simulation, we compare the usability and performance of our model in comparison with the widely used traditional access control model and role-based access control model. With business process outsourcing as an example, we demonstrate that our model also yields a considerable reduction in the number of access permissions to be managed by an administrator as compared with other two models. Simulations show an improvement in the time required for access authorization in our model as compared with these two models. These improvements exhibited by our model become more prominent with the increase in the number of users and objects.

Evidently, COVID-19 has changed our lives and is likely to make a lasting impact on our economic development and our industry and services. In the ongoing process of digital transformation in industry and services, Collaborative Networks (CNs) is required to be more efficient, productive, flexible, resilient and sustainable according to change of situations and related rules applied afterwards. Although the CN area is relatively young, it requires the previous research to be extended, i.e. business process management from dealing with processes within a single organization into processes across different organizations. In this paper, we review current business process verification and compliance research. Different tools approaches and limitations of them are compared. The further research issues and potential solutions of business process verification and compliance check are discussed in the context of CNs.

CafeOBJ is a language for specifying and verifying a wide variety of software and/or hardware systems. Traditionally, verification has been carried out via proof scores, which consist of reducing goal-related terms in user-defined modules. Although proof scores are semi-formal (the specifier is partially responsible for soundness), their flexibility makes them a useful approach to verification. For the last years, we have developed different formal tools around the CafeInMaude interpreter, a CafeOBJ interpreter implemented in Maude. Besides supporting proof scores, we implemented a theorem prover, a proof script generator from proof scores, and the first stages of a proof script generator and fixer-upper. In this paper, we present (i) an improved and detailed version of our proof script generator and fixer-upper and (ii) a reimplementation of the CafeInMaude interpreter, which supports, among others, parallel execution, an improved tool integration, and an interactive user interface. The benchmarks used to evaluate the tools confirm the usefulness of the approach.

Effective verification and validation are central to medical device software development and are essential for regulatory approval. Although guidance is available in multiple standards in the medical device software domain, it is difficult for the manufacturer to implement as there is no consolidated view of this information. Likewise, the standards and guidance documents do not consider process improvement initiatives. This paper assists in relation to both these aspects and introduces the development of processes for verification and validation in the medical device domain.

The benefits of effective verification and validation activities in the medical device domain include increased usability and reliability, decreased failure rate and recalls and reduced risks to patients and users. Though there is guidance on verification and validation in multiple standards in the medical device domain, these are difficult for the manufacturer to implement, as there is no consolidated information on how they can be successfully achieved. The paper highlights three major areas for improvement in the medical device software development domain. This research is based on an analysis of available literature in the field of verification and validation in generic software development, safety-critical and medical device software domains. Additionally, we also performed a review of the standards and process improvement models available in these domains.

The hardware description language Verilog has been standardized and widely used in industry. Multithreaded Discrete Event Simulation Language (MDESL) is a Verilog-like language and it contains a rich variety of interesting features such as the event-driven computation and shared-variable concurrency as well as the realtime feature. In this paper, we present the denotational semantics for MDESL based on UTP. First a discrete time semantic model is proposed to describe the observation-oriented semantics for MDESL. The observations record the change of variables of atomic actions over time. Then the healthy formulae are defined to denote all different behaviors of programs and the semantics of programs is expressed in terms of healthy formulae. In addition, we demonstrate some interesting properties about the MDESL programs expressing as algebraic laws and their proofs are supported by our formalized denotational semantics. Our theoretical approach is complemented by a practical one, w...

This Electronic Workshop in Computing (eWiC) proceedings contains selected papers from the workshop on Formal Methods in Industry, held in London, UK, and organised under the auspices of the BCS Formal Aspects of Computing Science (FACS) Specialist Group. The workshop, organised by Paul Boca, Jonathan Bowen and Peter Gorm Larsen, was inspired by the very successful and well-attended Industry Day event at the FM05 conference. The FACS workshop dovetails well with the subsequent Industry Day at FM08, which Peter Gorm Larsen is also co-chairing.

Enterprises are growing in complexity due to many business processes. This growth requires a simple but complete model for enterprise design. The DEMO model has proven its ability to describe an enterprise in a concise, coherent, and complete manner over the last decade. However, validating the model in the real world requires methods that enable debugging and testing the model, which can be achieved by simulating the model. In this paper, a simulation methodology is proposed. The methodology is based on mapping one to one from the DEMO model to Coloured Petri Net. The reason for choosing CPN is to use the richness of the Petri Net research results on, e.g., performance, deadlock analysis, animation, etc. Furthermore, CPN has a mathematical representation, which can initiate research on analysing DEMO models mathematically. As for validation, this paper applied the proposed transformation method to a case study.

Fractal interpolation provides an efficient way to describe data that have an irregular or self-similar structure. Fractal interpolation literature focuses mainly on functions, i.e. on data points linearly ordered with respect to their abscissa. In practice, however, it is often useful to model curves as well as functions using fractal intepolation techniques. After reviewing existing methods for curve fitting using fractal interpolation, we introduce a new method that provides a more economical representation of curves than the existing ones. Comparative results show that the proposed method provides smaller errors or better compression ratios.

Some years ago, several authors tried to construct fractal surfaces which pass through a given set of data points. They used bivariable functions on rectangular grids, but the resulting surfaces failed to be continuous. A method based on their work for generating fractal interpolation surfaces is presented. Necessary conditions for the attractor of an iterated function system to be the graph of a continuous bivariable function which interpolates a given set of data are also presented here. Moreover, a comparative study for four of the most important constructions and attempts on rectangular grids is considered which points out some of their limitations and restrictions.

For most high level languages, two procedures are equivalent if they transform a pair of isomorphic stores to isomorphic stores. However, tools for modular checking of such equivalence impose a stronger check where isomorphism is strengthened to equality of stores. This results in the inability to prove many interesting program pairs with recursion and dynamic memory allocation. In this work, we present RIE, a methodology to modularly establish equivalence of procedures in the presence of memory allocation, cyclic data structures and recursion. Our technique addresses the need for finding witnesses to isomorphism with angelic allocation, supports reasoning about equivalent procedures calls when the stores are only locally isomorphic, and reasoning about changes in the order of procedure calls. We have implemented RIE by encoding it in the Boogie program verifier. We describe the encoding and prove its soundness.

We are proud to present a Special Issue on Refinement, originating from the tenth BCS FACS Refinement Workshop, held in 2005. After the ninth workshop was held in 2002 (with a dedicated special issue in Volume 15(2-3) of this journal), UK researchers in the area have been collaborating through the EPSRC RefineNet network, see www.refinenet.org.uk. The organisation of a regular Refinement Workshop in conjunction with BCS FACS is part of the RefineNet remit, and one was held in April 2005, co-located with the ZB conference at the University of Surrey. The next edition will be held at Macao in October 2006, co-located with ICFEM. Workshop proceedings were published in Electronic Notes in Theoretical Computer Science, Volume 137(2). After the workshop, presenters were invited to submit significantly extended papers for inclusion in this special issue; five of these were accepted and have been included here. We, the editors of this Special Issue, are grateful to 'Formal Aspects of Computing' for allowing us to publish this collection of papers in the journal, and for a very pleasant collaboration; to the joint workshop chair J. Derrick and all others who made the workshop such a success by their participation, and to the reviewers involved in selecting the following papers. In "Verifying data refinements using a model checker", Smith and Derrick harness a model checker (SAL for CTL) for checking simulation-based data refinement between Z specifications. The paper by Cavalcanti, Woodcock and Dunne on "Angelic nondeterminism in the unifying theories of programming" shows how angelic and demonic choice together can be embedded in Hoare and He's unifying theories, using binary multirelations. "Tank monitoring: a pAMN case study" by Schneider, Hoang, Robinson and Treharne shows the application of probabilistic B to a small case study. "An analysis of refinement in an abortive paradigm" by Deutsch and Henson provides a model-theoretic account of refinement in the firing conditions interpretation of relational specifications. "The specification logic νZ" by Henson, Deutsch and Kajtazi builds on work by Henson and Reeves to develop a wide-spectrum specification logic similar to Z. The papers presented here have been fully re-reviewed following the normal procedures of the Formal Aspects of Computing Journal.

ABZ2008 Conference Short Papers September 16-18, 2008 BCS London Offices, Covent Garden, London, UK Egon Börger Michael Butler Jonathan Bowen Paul Boca ... ABZ2008 Short Papers Page 3 Anthony Hall. Integrating Z into Large Projects: Tools and Techniques 6 Joelle Cohen and Anatol Slissenko. Stability of Real-time Abstract State Machines 9 Roozbeh Farahbod and Uwe Glaesser. Dynamic Resource Configuration & Management for Distributed Information Fusion in Maritime Surveillance 12 Abderrahman Matoussi, Frederic Gervais and Regine ...

Developing safety critical software is a complex process. Due to the fact that medical device software failure can lead to catastrophic consequences, numerous standards have been developed which govern software development in the medical device domain. Risk management has an important role in medical device software development as it is important to ensure that safe software is developed. Demonstrating traceability of requirements right throughout the medical device software development and maintenance lifecycles is an important part of demonstrating that 'safe' software has been produced through adopting defined processes. Consequently, medical device standards and guidelines emphasise the need for traceability. This paper outlines the extent and diversity of traceability requirements within medical device standards and guidelines, and identifies the requirements for traceability through each phase of the software development lifecycle. The paper also summarises the findings obtained when a lightweight assessment method (Med-Trace), that we created, based upon the traceability practices within these standards, was implemented in two SME organisations. Finally we highlight how the findings indicate a lack of guidance as to what is required when implementing and maintaining a traceability process.

In the present work, the notion of Super Fractal Interpolation Function (SFIF) is introduced for finer simulation of the objects of nature or outcomes of scientific experiments that reveal one or more structures embedded in to another. In the construction of SFIF, an IFS is chosen from a pool of several IFSs at each level of iteration leading to implementation of the desired randomness and variability in fractal interpolation of the given data. Further, an expository description of our investigations on the integral, the smoothness and determination of conditions for existence of derivatives of an SFIF is given in the present work.

In the present work, the notion of Super Fractal Interpolation Function (SFIF) is introduced for finer simulation of the objects of nature or outcomes of scientific experiments that reveal one or more struc- tures embedded in to another. In the construction of SFIF, an IFS is chosen from a pool of several IFSs at each level of iteration leading to implementation of the desired randomness and variability in fractal interpolation of the given data. Further, an expository description of our investigations on the integral, the smoothness and determination of conditions for existence of derivatives of an SFIF is given in the present work.

Formal verification has long been promised as a means of reducing the amount of testing required to ensure correct VLSI devices. Verification requires at least two mathematical models: one that describes the structure of a computer system and another that models its intended behavior. These models are called specijkations. Verification is a mathematical analysis showing that the behavior follows from the structure. Formal verification of microprocessor designs has been quite successful. Indeed, several verified microprocessors have been presented in the literature, and one microprocessor where formal modeling has been applied is commercially available. These efforts were virtuoso performances-largely academic exercises carried out by experts in logic and specification. This paper presents a methodology for microprocessor verification that significantly reduces the learning curve for performing verification. The methodology is formalized in the HOL theoremproving system. The paper includes a description of a large case study performed to evaluate the methodology. The novel aspects of this research include the use of abstract theories to formalize hardware models. Because our model is described using abstract theories, it provides a framework for both the specification and the verification. This framework reduces the number of ad hoc modeling decisions that must be made to complete the verification. Another unique aspect of our research is the use of hierarchical abstractions to reduce the number of difficult lemmas in completing the verification. Our formalism frees the user from directly reasoning about the difficult aspects of modeling the hierarchy, namely the temporal and data abstractions. We believe that our formalism, coupled with case studies and tools, allows microprocessor verification to be done by engineers with relatively little experience in microprocessor specification or logic. We are currently testing that hypothesis by using the methodology to teach graduate students formal microprocessor modeling. I. INTRODUCTION OMPUTERS are being used with increasing frequency C in areas in which the correct implementation of the computer hardware is critical. Testing has traditionally been used to exclude faults in computers; however, the effectiveness of testing is limited by the combinatorial explosion inherent in any testing technique. The limitations of testing, coupled with the ever-increasing size of VLSI devices, have led to a search for alternatives to testing, such as mathematical modeling and analysis.