Introduction to Milestones in Interactive Theorem Proving

On March 8, 2018, Tobias Nipkow celebrated his sixtieth birthday. In anticipation of the occasion, in January 2016, two of his former students, Gerwin Klein and Jasmin Blanchette, and one of his former postdocs, Andrei Popescu, approached the editorial board of the Journal of Automated Reasoning with a proposal to publish a surprise Festschrift issue in his honor. The e-mail was sent to twenty-six members of the board, leaving out one, for reasons that will become clear in a moment. It is a sign of the love and respect that Tobias commands from his colleagues that within two days every recipient of the e-mail had responded favorably and enthusiastically to the proposal

Dynamic update of discrete event controllers

Discrete event controllers are at the heart of many software systems that require continuous operation. Changing these controllers at runtime to cope with changes in its execution environment or system requirements change is a challenging open problem. In this paper we address the problem of dynamic update of controllers in reactive systems. We present a general approach to specifying correctness criteria for dynamic update and a technique for automatically computing a controller that handles the transition from the old to the new specification, assuring that the system will reach a state in which such a transition can correctly occur and in which the underlying system architecture can reconfigure. Our solution uses discrete event controller synthesis to automatically build a controller that guarantees both progress towards update and safe update

Bowdoin Orient v.89, no.1-22 (1959-1960)

https://digitalcommons.bowdoin.edu/bowdoinorient-1960s/1000/thumbnail.jp

A framework for analyzing changes in health care lexicons and nomenclatures

Ontologies play a crucial role in current web-based biomedical applications for capturing contextual knowledge in the domain of life sciences. Many of the so-called bio-ontologies and controlled vocabularies are known to be seriously defective from both terminological and ontological perspectives, and do not sufficiently comply with the standards to be considered formai ontologies. Therefore, they are continuously evolving in order to fix the problems and provide valid knowledge. Moreover, many problems in ontology evolution often originate from incomplete knowledge about the given domain. As our knowledge improves, the related definitions in the ontologies will be altered. This problem is inadequately addressed by available tools and algorithms, mostly due to the lack of suitable knowledge representation formalisms to deal with temporal abstract notations, and the overreliance on human factors. Also most of the current approaches have been focused on changes within the internal structure of ontologies, and interactions with other existing ontologies have been widely neglected. In this research, alter revealing and classifying some of the common alterations in a number of popular biomedical ontologies, we present a novel agent-based framework, RLR (Represent, Legitimate, and Reproduce), to semi-automatically manage the evolution of bio-ontologies, with emphasis on the FungalWeb Ontology, with minimal human intervention. RLR assists and guides ontology engineers through the change management process in general, and aids in tracking and representing the changes, particularly through the use of category theory. Category theory has been used as a mathematical vehicle for modeling changes in ontologies and representing agents' interactions, independent of any specific choice of ontology language or particular implementation. We have also employed rule-based hierarchical graph transformation techniques to propose a more specific semantics for analyzing ontological changes and transformations between different versions of an ontology, as well as tracking the effects of a change in different levels of abstractions. Thus, the RLR framework enables one to manage changes in ontologies, not as standalone artifacts in isolation, but in contact with other ontologies in an openly distributed semantic web environment. The emphasis upon the generality and abstractness makes RLR more feasible in the multi-disciplinary domain of biomedical Ontology change management

On the edge of mystery towards a spiritual hermeneutic of the urban margins

The questions explored in this thesis are: whether it is possible to have a shared spirituality between those who work on the urban margins and the people with whom they work; and what factors might assist such a reciprocal sense of depth exchange?The focus for the empirical work was on a situation where a group of religious and lay women are living and working on a peripheral urban housing estate. Although it was necessary to employ sociological research methods, this is not a sociological case study, but rather the exploration of lived spirituality within the Christian tradition.The emerging importance of conversation and dialogue leads to interaction with Gadamer and Tracy. The work of Rahner, particularly his emphasis on the dynamic drive towards divine mystery inherent within humanity, proves important, as it becomes evident that by virtue of their own discovery of the transcendent, the people of the estate are celebrating grace, but have come to it in and through the sacrament of their own lives.It is suggested that this operative fact of grace at work amongst the marginalised merits further consideration by the church. Here the vital function of a critical listening faculty is imperative. Indeed, it is suggested that such a developed faculty has more universal applicability throughout all forms of ministry. The facilitative tool for such an attuned listening is seen to be the openness to engagement with the contemplative dimension. Thus there is a re-engagement with the classical spiritual tradition, which is seen to authenticate the integrated nature of contemplation and action. Finally, detailed consideration is given to the process of the interior journey and the qualities engendered along the way vital for a contemporary spiritual hermeneutic. Here interaction with the work of Merton proves invaluable.Thus the course of the thesis is an unfolding of a spiritual hermeneutic which, it is suggested, has ramifications not exclusively on the urban margins, but as a potential dynamic force within the church at the close of the twentieth century

Computer Aided Verification

This open access two-volume set LNCS 11561 and 11562 constitutes the refereed proceedings of the 31st International Conference on Computer Aided Verification, CAV 2019, held in New York City, USA, in July 2019. The 52 full papers presented together with 13 tool papers and 2 case studies, were carefully reviewed and selected from 258 submissions. The papers were organized in the following topical sections: Part I: automata and timed systems; security and hyperproperties; synthesis; model checking; cyber-physical systems and machine learning; probabilistic systems, runtime techniques; dynamical, hybrid, and reactive systems; Part II: logics, decision procedures; and solvers; numerical programs; verification; distributed systems and networks; verification and invariants; and concurrency

Ownership-based order reduction and simulation in shared-memory concurrent computer systems

The highest level of confidence in the correct functionality of system software can be gained from a pervasive formal verification approach, where the high-level language application layer is connected to the gate-level hardware layer through a stack of semantic layers coupled by simulation theorems. While such semantic stacks exist for sequential systems, the foundational theory of semantic stacks for concurrent systems is still incomplete. This thesis contributes to close this gap. First we prove a general order reduction theorem establishing a model where processes are executing blocks of steps, being only interleaved at selectable interleavingpoints. An ownership-based memory access policy is imposed to prove commutativity properties for non-synchronizing steps, enabling the desired reordering. In contrast to existing work, we only assume properties on the order-reduced level, thus providing a complete abstraction. We then apply sequential simulation theorems on top of the block schedules and prove a general simulation theorem between two abstract concurrent systems including the transfer of safety properties. Finally we instantiate our frameworks with a MIPS instruction set architecture, a macro assembler (MASM) semantics, and an intermediate language semantics for C. Applying the concurrent simulation theorem, we justify the concurrent semantics of MASM and C against their ISA implementation.Das größte Vertrauen in die korrekte Funktionsweise von System-Software kann mit Hilfe durchdringender formaler Beweisverfahren erlangt werden, welche alle Abstraktionsebenen eines Computersystems durch Simulationstheoreme miteinander koppeln. Während solche Gerüste von Semantiken bereits für sequentielle Systeme entwickelt wurden, finden sich in der entsprechenden Theorie für nebenläufige Systeme noch Lücken, zur Schließung derer diese Arbeit beitragen soll. Zunächst beweisen wir ein allgemeines Reduktionstheorem, das die möglichen Reihenfolgen, in der Prozesse Schritte machen, auf ein Modell beschränkt, in dem Blöcke von Schritten verschiedener Prozesse nacheinander ausgeführt werden. Mittels eines ”Ownership”-basierten Speicherzugriffprotokolls beweisen wir Kommutativitätseigenschaften für lokale Schritte verschiedener Prozesse und ermöglichen so das Vertauschen dieser. Da unser Theorem nur Eigenschaften des reihenfolgereduzierten Systems annimmt ermöglicht es eine vollständige Abstraktion vom ursprünglichen Modell. Auf die Blockausführung wenden wir sequentielle Simulationstheoreme an und beweisen ein allgemeines Simulationstheorem zwischen abstrakten nebenläufigen Systemen sowie den Transfer von Sicherheitseigenschaften. Wir instanziieren das Theorem mit einem MIPS-Instruktionssatz und Semantiken für Makroassembler und C. Dadurch rechtfertigen wir die nebenläufige Semantik der Programmiersprachen gegen ihre Maschinenimplementierung