11 research outputs found
Edsger W. Dijkstra: a Commemoration
This article is a multiauthored portrait of Edsger Wybe Dijkstra that consists of testimonials written by several friends, colleagues, and students of his. It provides unique insights into his personality, working style and habits, and his influence on other computer scientists, as a researcher, teacher, and mentor
Second-Order Functions and Theorems in ACL2
SOFT ('Second-Order Functions and Theorems') is a tool to mimic second-order
functions and theorems in the first-order logic of ACL2. Second-order functions
are mimicked by first-order functions that reference explicitly designated
uninterpreted functions that mimic function variables. First-order theorems
over these second-order functions mimic second-order theorems universally
quantified over function variables. Instances of second-order functions and
theorems are systematically generated by replacing function variables with
functions. SOFT can be used to carry out program refinement inside ACL2, by
constructing a sequence of increasingly stronger second-order predicates over
one or more target functions: the sequence starts with a predicate that
specifies requirements for the target functions, and ends with a predicate that
provides executable definitions for the target functions.Comment: In Proceedings ACL2 2015, arXiv:1509.0552
Simplifying the Analysis of C++ Programs
Based on our experience of working with different C++ front ends, this thesis identifies numerous problems that complicate the analysis of C++ programs along the entire spectrum of analysis applications. We utilize library, language, and tool extensions to address these problems and offer solutions to many of them. In particular, we present efficient, expressive and non-intrusive means of dealing with abstract syntax trees of a program, which together render the visitor design pattern obsolete. We further extend C++ with open multi-methods to deal with the broader expression problem. Finally, we offer two techniques, one based on refining the type system of a language and the other on abstract interpretation, both of which allow developers to statically ensure or verify various run-time properties of their programs without having to deal with the full language semantics or even the abstract syntax tree of a program. Together, the solutions presented in this thesis make ensuring properties of interest about C++ programs available to average language users
Deductive verification of object-oriented software : dynamic frames, dynamic logic and predicate abstraction
Software systems play a central role in modern society, and their correctness is often crucially important. Formal specification and verification are promising approaches for ensuring correctness more rigorously than just by testing. This work presents an approach for deductively verifying design-by-contract specifications of object-oriented programs. The approach is based on dynamic logic, and addresses the challenges of modularity and automation using dynamic frames and predicate abstraction
Robust Verteilte Software Transaktionen für Haskell
This thesis motivates and develops a robust distributed Software Transactional Memory (STM) library for Haskell. Many real-life applications are distributed by nature. They either control geographically wide spread hardware resources or utilize redundant hardware components to minimize system failure. STM is an abstraction for synchronizing shared resources in concurrent applications. It helps to prevent deadlocks and thus facilitates composing program code.
We extend the STM abstraction to distributed systems and present an implementation efficient enough to be used in soft real-time applications. Further, the implemented library is robust in itself, offering the application developer a high abstraction level to realize robustness, hence, significantly simplifying this, in general, complex task.Die vorliegende Arbeit motiviert und entwickelt eine robuste, verteilte Software Transactional Memory (STM) Bibliothek für Haskell. Viele reale Anwendungen sind von Natur aus verteilt. Sie steuern entweder geografisch weit verteilte Ressourcen oder nutzen redundante Hardware-Komponenten, um Systemfehler zu verringern. STM ist eine Abstraktion, um gemeinsame Ressourcen in nebenläufigen Anwendungen zu synchronisieren. Sie hilft Verklemmungen zu verhindern und vereinfacht dadurch die Komposition des Programmcodes.
Wir erweitern die STM-Abstraktion auf verteilte Systeme und präsentieren eine Implementierung, die effizient genug ist, um in weichen Echtzeit-Anwendungen genutzt zu werden. Weiterhin ist die implementierte Bibliothek selbst robust und bietet damit dem Anwendungsprogrammierer ein hohes Maß an Abstraktion, um Robustheit zu verwirklichen, was ihm diese, im Allgemeinen, komplexe Aufgabe deutlich erleichtert
An Assertional Proof System for Multithreaded Java - Theory and Tool Support
Besides the features of a class-based object-oriented language, Java integrates concurrency via its thread classes, allowing for a multithreaded flow of control. The concurrency model includes shared-variable concurrency via instance variables, coordination via reentrant synchronization monitors, synchronous message passing, and dynamic thread creation. To reason about safety properties of multithreaded Java programs, we introduce a tool-supported assertional proof method for JavaMT ("Multi-Threaded Java"), a small sublanguage of Java, covering the mentioned concurrency issues as well as the object-based core of Java. The verification method is formulated in terms of proof-outlines, where the assertions are layered into local ones specifying the behavior of a single instance, and global ones taking care of the connections between objects. We establish the soundness and the completeness of the proof system. From an annotated program, a number of verification conditions are generated and handed over to the interactive theorem prover PVS.IST project Omega (IST-2001-33522) NWO/DFG project Mobi-J (RO 1122/9-1, RO 1122/9-2)UBL - phd migration 201
An Assertional Proof System for Multithreaded Java - Theory and Tool Support
Besides the features of a class-based object-oriented language, Java integrates concurrency via its thread classes, allowing for a multithreaded flow of control. The concurrency model includes shared-variable concurrency via instance variables, coordination via reentrant synchronization monitors, synchronous message passing, and dynamic thread creation. To reason about safety properties of multithreaded Java programs, we introduce a tool-supported assertional proof method for JavaMT ("Multi-Threaded Java"), a small sublanguage of Java, covering the mentioned concurrency issues as well as the object-based core of Java. The verification method is formulated in terms of proof-outlines, where the assertions are layered into local ones specifying the behavior of a single instance, and global ones taking care of the connections between objects. We establish the soundness and the completeness of the proof system. From an annotated program, a number of verification conditions are generated and handed over to the interactive theorem prover PVS.IST project Omega (IST-2001-33522) NWO/DFG project Mobi-J (RO 1122/9-1, RO 1122/9-2)UBL - phd migration 201