Termination of rewriting strategies: a generic approach

We propose a generic termination proof method for rewriting under strategies, based on an explicit induction on the termination property. Rewriting trees on ground terms are modeled by proof trees, generated by alternatively applying narrowing and abstracting steps. The induction principle is applied through the abstraction mechanism, where terms are replaced by variables representing any of their normal forms. The induction ordering is not given a priori, but defined with ordering constraints, incrementally set during the proof. Abstraction constraints can be used to control the narrowing mechanism, well known to easily diverge. The generic method is then instantiated for the innermost, outermost and local strategies.Comment: 49 page

Strategic Computation and Deduction

We introduce the notion of abstract strategies for abstract reduction systems. Adequate properties of termination, confluence and normalization under strategy can then be defined. Thanks to this abstract concept, we draw a parallel between strategies for computation and strategies for deduction. We define deduction rules as rewrite rules, a deduction step as a rewriting step and a proof construction step as a narrowing step in an adequate abstract reduction system. Computation, deduction and proof search are thus captured in the uniform foundational concept of abstract reduction system in which abstract strategies have a clear formalisation

Narrowing Based Inductive Proof Search

Premiere version en 2005, en l'honneur de Harald GanzingerVersion finale envoyé a SpringerWe present in this paper a narrowing-based proof search method for inductive theorems. It has the specificity to be grounded on deduction modulo and to yield a direct translation from a successful proof search derivation to a proof in the sequent calculus. The method is shown to be sound and refutationally correct in a proof theoretical way

A Port Graph Calculus for Autonomic Computing and Invariant Verification

International audienceIn this paper, we first introduce port graphs as graphs with multiple edges and loops, with nodes having explicit connection points, called ports, and edges attaching to ports of nodes. We then define an abstract biochemical calculus that instantiates to a rewrite calculus on these graphs. Rules and strategies are themselves port graphs, i.e. first-class objects of the calculus. As a consequence, they can be rewritten as well, and rules can create new rules, providing a way of modeling adaptive systems. This approach also provides a formal framework to reason about computations and to verify useful properties. We show how structural properties of a modeled system can be expressed as strategies and checked for satisfiability at each step of the computation. This provides a way to ensure invariant properties of a system. This work is a contribution to the formal specification and verification of adaptive systems and to theoretical foundations ofautonomic computing

Semi-Automatic Synthesis of Security Policies by Invariant-Guided Abduction - Full version

We present a specification approach of secured systems as transition systems and security policies as constraints that guard the transitions. In this context, security properties are expressed as invariants. Then we propose an abduction algorithm to generate possible security policies for a given transition-based system. Because abduction is guided by invariants, the generated security policies enforce security properties specified by these invariants. In this framework we are able to tune abduction in two ways in order to: (i) filter out bad security policies and (ii) generate additional possible security policies. Invariant-guided abduction helps designing policies and thus allows using formal methods much earlier in the process of building secured systems. This approach is illustrated on role-based access control systems

A Strategy Language for Graph Rewriting

International audienceWe give a formal semantics for a graph-based programming language, where a program consists of a collection of graph rewriting rules, a user-defined strategy to control the application of rules, and an initial graph to be rewritten. The traditional operators found in strategy languages for term rewriting have been adapted to deal with the more general setting of graph rewriting, and some new constructs have been included in the language to deal with graph traversal and management of rewriting positions in the graph. This language is part of the graph transformation and visualisation environment PORGY

open-access.network. Wie gestalten wir die Zukunft?

Das Poster "open-access.network. Wie gestalten wir die Zukunft?" wurde im Rahmen des BMBF-geförderten Projekts open.access-network erstellt und für die Open-Access-Tage 2023 angenommen. Das Poster skizziert den Weg zur Verstetigung des Kompetenz- und Vernetzungsportals open-access.network. Mit Blick auf das Ziel eines Community-basierten Organisations- und Finanzierungsmodells, wird aktiv zur Interaktion mit dem Poster sowie zur Ideen- und Meinungsäußerung zur Verstetigung eingeladen

Experimental Research in Synthetic Molecular Communications -- Part I: Overview and Short-Range Systems

Since its emergence from the communication engineering community around one and a half decades ago, the field of Synthetic Molecular Communication (SMC) has experienced continued growth, both in the number of technical contributions from a vibrant community and in terms of research funding. Throughout this process, the vision of SMC as a novel, revolutionary communication paradigm has constantly evolved, driven by feedback from theoretical and experimental studies, respectively. It is believed that especially the latter ones will be crucial for the transition of SMC towards a higher technology readiness level in the near future. In this spirit, we present here a comprehensive survey of experimental research in SMC. In particular, this survey focuses on highlighting the major drivers behind different lines of experimental research in terms of the respective envisioned applications. This approach allows us to categorize existing works and identify current research gaps that still hinder the development of practical SMC-based applications. Our survey consists of two parts; this paper and a companion paper. While the companion paper focuses on SMC with relatively long communication ranges, this paper covers SMC over short distances of typically not more than a few millimeters.Comment: 10 pages, 1 table, 5 figures. Accepted for publication in the IEEE Nanotechnology Magazin

Experimental Research in Synthetic Molecular Communications -- Part II: Long-Range Communication

In this second part of our survey on experimental research in Synthetic Molecular Communication (SMC), we review works on long-range SMC systems, i.e., systems with communication ranges of more than a few millimeters. Despite the importance of experimental research for the evolution of SMC towards a mature communication paradigm that will eventually support revolutionary applications beyond the reach of today's prevalent communication paradigms, the existing body of literature is still comparatively sparse. Long-range SMC systems have been proposed in the literature for information transmission in two types of fluid media, liquid and air. While both types of SMC systems, liquid-based and air-based systems, rely on encoding and transmitting information using molecules, they differ substantially in terms of the physical system designs and in the type of applications they are intended for. In this paper, we present a systematic characterization of experimental works on long-range SMC that reveals the major drivers of these works in terms of the respective target applications. Furthermore, the physical designs for long-range SMC proposed in the literature are comprehensively reviewed. In this way, our survey will contribute to making experimental research in this field more accessible and identifying novel directions for future research.Comment: 10 pages, 2 tables, 4 figures. Accepted for publication in the IEEE Nanotechnology Magazin

Constraint Based Strategies

International audienceNumerous computational and deductive frameworks use the notion of strategy to guide reduction and search space exploration, making the macro scale control of micro operations an explicit object of interest. In recent works, abstract strategies have been defined in extension but also intensionally. In this paper we complete these views with a new declarative approach based on constraints, which are used to model the different parts of a strategy. This procedure allows us to express elaborate strategies in a declarative and reusable way