Z2SAL: a translation-based model checker for Z

Despite being widely known and accepted in industry, the Z formal specification language has not so far been well supported by automated verification tools, mostly because of the challenges in handling the abstraction of the language. In this paper we discuss a novel approach to building a model-checker for Z, which involves implementing a translation from Z into SAL, the input language for the Symbolic Analysis Laboratory, a toolset which includes a number of model-checkers and a simulator. The Z2SAL translation deals with a number of important issues, including: mapping unbounded, abstract specifications into bounded, finite models amenable to a BDD-based symbolic checker; converting a non-constructive and piecemeal style of functional specification into a deterministic, automaton-based style of specification; and supporting the rich set-based vocabulary of the Z mathematical toolkit. This paper discusses progress made towards implementing as complete and faithful a translation as possible, while highlighting certain assumptions, respecting certain limitations and making use of available optimisations. The translation is illustrated throughout with examples; and a complete working example is presented, together with performance data

Coordination via Interaction Constraints I: Local Logic

Wegner describes coordination as constrained interaction. We take this approach literally and define a coordination model based on interaction constraints and partial, iterative and interactive constraint satisfaction. Our model captures behaviour described in terms of synchronisation and data flow constraints, plus various modes of interaction with the outside world provided by external constraint symbols, on-the-fly constraint generation, and coordination variables. Underlying our approach is an engine performing (partial) constraint satisfaction of the sets of constraints. Our model extends previous work on three counts: firstly, a more advanced notion of external interaction is offered; secondly, our approach enables local satisfaction of constraints with appropriate partial solutions, avoiding global synchronisation over the entire constraints set; and, as a consequence, constraint satisfaction can finally occur concurrently, and multiple parts of a set of constraints can be solved and interact with the outside world in an asynchronous manner, unless synchronisation is required by the constraints. This paper describes the underlying logic, which enables a notion of local solution, and relates this logic to the more global approach of our previous work based on classical logic

Understanding Cognition Across Modalities for the Assessment of Digital Resources

Drawing from the theories of the cognitive process, this paper explores the transmission, retention and transformation of information across oral, written, and digital modes of communication and how these concepts can be used to examine the assessment of digital resource tools. The exploration of interactions across modes of communication is used to gain an understanding of the interaction between the student, digital resource and teacher. Cognitive theory is considered as a basis for the assessment of digital resource tools. Lastly, principles for the assessment of digital resource tools are presented along with how assessment can be incorporated in the educational practice to enhance learning in higher education

Reluctant Bedfellows or Model Marriage? : Postmodern Thinking Applied to Mainstream Public Sector Health Services Research Settings

An important mobilisation of postmodernism is as a way of thinking that pays particular attention to the play of differences in human thought and experience. Informed by the Derridean theory of deconstruction, the current discussion critically examines an original piece of health services research undertaken by the author, which aimed to derive propositions about how health service researchers disseminated research information to those in daily practice in the United Kingdom (UK) National Health Service (NHS). The objective is to provide an analytical review of those tacit and oftentimes suppressed, marginalized or hidden, forms of knowledge that may be conveniently overlooked or glossed over in mainstream health services research, which is largely produced by university-based researchers who remain subject to traditional academic pressures. Following a review of the theory and practice of deconstruction, Boje and Dennehy’s (1994) specific seven-point ‘deconstruction methodology’, based on drawing empirical data through bipolar opposite themes, is deployed before concluding with a consideration of the implications of a postmodern analysis of mainstream healthcare practice, policy and organisation settings, which have a central role to play in delivering service improvement in the new financial environment

MACH2: System for Root Cause Analysis of Kernel Vulnerabilities

Kernel code is ubiquitous in the modern technology landscape, and therefore, enforcing its security is of high importance. A common problem among modern kernel fuzzers is the discovery of vulnerabilities whose causes are difficult to pinpoint, meaning that they cannot easily be patched by developers. This leads to a large accumulation of bugs for kernel and kernel driver code. This issue can be remediated by being able to trace the root cause of a given exploit in the original source code. This study introduces MACH2, a system through which kernel vulnerabilities can have their root causes pinpointed such that they can be easily corrected by developers and/or automated systems. The MACH2 system consists of a 2-stage process: first, the system generates a trace of the exploit being run, and then, it uses this trace in tandem with a DSE engine to find the input regions of the code corresponding to the vulnerability at hand. MACH2 has already demonstrated its usability against CVEs and real-world exploits, and with upcoming additions, will be able to handle a wide array of vulnerability classes, allowing for a more secure kernel code landscape.Undergraduat