Dynamic Logic with Trace Semantics

Dynamic logic is an established instrument for program verification and for reasoning about the semantics of programs and programming languages. In this paper, we define an extension of dynamic logic, called Dynamic Trace Logic (DTL), which combines the expressiveness of program logics such as dynamic logic with that of temporal logic. And we present a sound and relatively complete sequent calculus for proving validity of DTL formulae. Due to its expressiveness, DTL can serve as a basis for proving functional and information-flow properties in concurrent programs, among other applications

FAKTOR2: A Code to Simulate Collective Effects of Electrons and Ions

A new code for computing multiple effects of nonrelativistic charges is being developed. The basic method is electrostatic Particle in Cell. The underlying grid is rectangular and locally homogeneous. At regions of interest, eg. where the beam is, or near material boundaries, the mesh is refined recursively. The motion of the macroparticles is integrated with an adapted time step. Fast particles are treated with a smaller time step, and particles in regions of fine grids are also treated with a fine time step. The position of collision of particles with material boundaries are accurately resolved. Secondary particles are then created according to user specified yield functions

Ion Effects in the Damping Rings of ILC and CLIC

We discuss ion trapping, rise time of fast beam-ion instability, and ion-induced incoherent tune shift for various incarnations of the ILC damping rings and for the CLIC damping ring, taking into account the different regions of each ring. Analytical calculations for ion trapping are compared with results from a new simulation code

Gattungshistorische Überlegungen mit Einzelstudien zur Epik des italienischen Quattrocento und der französischen Renaissance

Das vorliegende Working Paper untersucht transhistorische Filiationen aktualitätsepischen Schreibens von der Antike bis in die Frühe Neuzeit. Ausgehend von purifizierend vereinfachenden Grundannahmen der Moderne, die das Epos allein auf ideologiestabilisierende Narrative einer mythhistorischen Vorzeit beschränken (z.B. Bachtin), sollen hier zum einen die seit der Antike bestehende und in ihrer Quantität bedeutsame Tradition von zeithistorischer Epik und zum anderen anhand ausgewählter Epen, insbesondere aus dem italienischen Quattrocento und der französischen Renaissance, die zuweilen sehr produktive Spannung zwischen ‚alter‘ literarischer Gattung und ‚neuem‘ historischen Stoff aufgezeigt werden. Das Working Paper erweitert damit die Perspektive des Teilprojekts 03 („Die Pistole des Mars“) im Hinblick auf andere zeitliche und räumliche Kontexte. Die exemplarischen Studien sollen zeigen, dass der Rekurs auf die epische(n) Gattungstradition(en) keineswegs einheitlich ist, sondern äußerst heterogen ausfällt. Neben dem vergilischen Paradigma eines herrschaftspanegyrischen, teleologischen Großnarrativs mit einer theologisch-heilsgeschichtlichen Komponente (Tito Strozzi, Borsias), lässt sich ebenso aufgrund des zunehmenden Interesses an der griechischen Literatur im 15. Jahrhundert eine Homerisierung der Epik feststellen (Basinio da Parma, Hesperis). Die Epik Frankreichs rezipiert zudem die Ritterstoffe des Mittelalters und koppelt diese mit den antiken Mustern (Sébastien Garnier, Henriade). Schließlich bildet die Bürgerkriegsepik Lucans einen virulenten Bezugspunkt in der Verarbeitung des französischen Konfessionskonflikts (Paulus Thomas, Lutetias)

Evidence Searching for Evidence-Based Psychology Practice

There is an increased awareness of evidence-based methodology among psychologists, but little exists in the literature about how to access the research. Moreover, the prohibitive cost of this information and limited time are barriers to the identification of evidence to answer clinical questions. This article presents an example of a question worked though in an evidence-based way. Methods are highlighted, including distinguishing background and foreground questions, breaking down questions into searchable statements, and adapting statements to suit both the question being asked and the resource being searched. A number of free, evidence-based resources are listed. Knowing how and where to access this information will enable practitioners to more easily use an evidence-based approach to their practice

Specification of Red-black Trees: Showcasing Dynamic Frames, Model Fields and Sequences

Complex data structures still pose a major challenge in specification and verification of object-oriented programs. Leino and Moskal have proposed a suite of benchmarks for verification tools, nicknamed "VACID-0". In contrast to similar papers, the tasks of VACID-0 do not only include verification in terms of an observable behavior but also of internal workings of algorithms and data structures. The arguably most difficult target are so-called red-black black trees. In this contribution, we present an implementation and specification in Java/JML* (i.e., KeY\u27s extension to JML with dynamic frames). It makes use of several new features: first and foremost the dynamic frame theory, model fields, the sequence ADT, as well as some newly supported features from standard JML

Deductive Verification of Concurrent Programs

Verification of concurrent programs still poses one of the major challenges in computer science. Several techniques to tackle this problem have been proposed. However, they often do not scale. We present an adaptation of the rely/guarantee methodology in dynamic logic. Rely/guarantee uses functional specification to symbolically describe the behavior of concurrently running threads: while each thread guarantees adherence to a specified property at any point in time, all other threads can rely on this property being established. This allows to regard threads largely in isolation--only w.r.t. an environment constrained by these specifications. While rely/guarantee based approaches often suffer from a considerable specification overhead, we complement functional thread specifications with frame conditions. We will explain our approach using a simple, but concurrent programing language. Besides the usual constructs for sequential programs, it caters for dynamic thread creation. We define semantics of concurrent programs w.r.t. an underspecified deterministic scheduling function. To formally reason about programs of this language, we introduce a novel multi-modal logic, Concurrent Dynamic Trace Logic (CDTL). It combines the strengthes of dynamic logic with those of linear temporal logic and allows to express temporal properties about symbolic program traces. We first develop a sound and complete sequent calculus for the logic subset that uses the sequential part of the language, based on symbolic execution. In a second step, we extend this to a calculus for the complete logic by adding symbolic execution rules for concurrent interleavings and dynamic thread creation based on the rely/guarantee methodology. Again, this calculus is proven sound and complete

Formal Verification of an Electronic Voting System

Electronic voting (e-voting) systems that are used in public elections need to fulfil a broad range of strong requirements concerning both safety and security. Among these requirements are reliability, robustness, privacy of votes, coercion resistance and universal verifiability. Bugs in or manipulations of an e-voting system may have considerable influence on the life of the humans living in a country where such a system is used. Hence, e-voting systems are an obvious target for software verification. In this paper, we report on an implementation of such a system in Java and the formal verification of functional properties thereof in the KeY verification system. Even though the actual components are clearly modularized, the challenge lies in the fact that we need to prove a highly nonlocal property: After all voters have cast their votes, the server calculates the correct votes for each candidate w.r.t. the original ballots. This kind of trace property is dificult to prove with static techniques like verification and typically yields a large specification overhead

Formal specification with JML

This text is a general, self contained, and tool independent introduction into the Java Modeling Language, JML. It is a preview of a chapter planned to appear in a book about the KeY approach and tool to the verification of Java software. JML is the dominating starting point of KeY style Java verification. However, this paper does not in any way depend on any tool nor verification methodology. Other chapters in this book talk about the usage of JML in KeY style verification. Here, we only refer to KeY in very few places, without relying on it. This introduction is written for all readers with an interest in formal specification of software in general, and anyone who wants to learn about the JML approach to specification in particular. The authors appreciate any comments or questions that help to improve the text