Egon Börger

Abstract State Machines

State Machines

The ASM refinement method

In this paper the abstract state machine (ASM) refinement method is presented. Its characteristics compared to other refinement approaches in the literature are explained. Some frequently occurring forms of ASM refinements are identified and illustrated by examples from the design and verification of architectures and protocols, from the semantics and the implementation of programming languages and from requirements engineering.

Java and the Java Virtual Machine

method declarations

An ASM Semantics for UML Activity Diagrams

We provide a rigorous semantics for one of the central diagram types which are used in UML for the description of dynamical system behavior, namely activity diagrams. We resolve for these diagrams some of the ambiguities which arise from difierent interpretations of UML models. Since we phrase our definition in terms of Abstract State Machines, we define at the same time an interesting subclass of ASMs, offering the possibility to exploit the UML tool support for using these special ASMs in the practice of software design. We apply these Activity Diagram Machines for a succinct definition of the semantics of OCCAM.

Modeling the Dynamics of UML State Machines

We define the dynamic semantics of UML State Machines which integrate statecharts with the UML object model. The use of ASMs allows us (a) to rigorously model the event driven run to completion scheme, including the sequential execution of entry/exit actions (along the structure of state nesting) and the concurrent execution of internal activities; (b) to formalize the object interaction, by combining control and data flow features in a seamless way; and (c) to provide a precise but nevertheless provably most general computational meaning to the UML terms of atomic and durative actions/activities. We borrow some features from the rigorous description of UML Activity Diagrams by ASMs in [7].

Approaches to modeling business processes: a critical analysis of BPMN, workflow patterns and YAWL

We investigate three approaches describing models of business processes: the OMG standard BPMN in its recent version 2.0, the workflow patterns of the Workflow Pattern Initiative and their reference implementation YAWL. We show how the three approaches fail to provide practitioners with a suitable means precisely and faithfully to capture business scenarios and to analyze, communicate and manage the resulting models. On the positive side, we distill from the discussion six criteria which can help to recognize practical and reliable tool-supported business process description and modeling systems.

A Programmer Friendly Modular Definition of the Semantics of Java

We propose in this paper a definition of the semantics of Java programs which can be used as a basis for the standardization of the language and of its implementation on the Java Virtual Machine. The definition provides a machine and system independent view of the language as it is seen by the Java programmer. It takes care to directly reflect the description in the Java language reference manual so that the basic design decisions can be checked by standardizers and implementors against a mathematical model. Our definition is the basis for a related definition we give in a sequel to this paper for the implementation of Java on the Java Virtual Machine as described in the language and in the Virtual Machine reference manuals.

Abstract State Machines 2003

Invited Papers.- Software Testing Research and Practice.- Abstract State Processes.- Recent Advances in Refinement.- Partial Updates Exploration II.- Experiments with Test Case Generation and Runtime Analysis.- A Framework for Proving Contract-Equipped Classes.- Mobile UNITY Schemas for Agent Coordination.- UML and Concurrency.- Research Papers.- A Unified Formal Specification and Analysis of the New Java Memory Models.- Modelling Conditional Knowledge Discovery and Belief Revision by Abstract State Machines.- Formal Description of a Distributed Location Service for Mobile Ad Hoc Networks.- Remarks on Turbo ASMs for Functional Equations and Recursion Schemes.- Integrating UML Static and Dynamic Views and Formalizing the Interaction Mechanism of UML State Machines.- The Hidden Computation Steps of Turbo Abstract State Machines.- Using Spin to Generate Tests from ASM Specifications.- Interfacing ASM with the MDG Tool.- ASMs versus Natural Semantics: A Comparison with New Insights.- Quantum Computing and Abstract State Machines.- Consistent Integration for Sequential Abstract State Machines.- Deciding the Verification Problem for Abstract State Machines.- An ASM Semantics of UML Derived from the Meta-model and Incorporating Actions.- Privacy, Abstract Encryption and Protocols: An ASM Model - Part I.- A Framework for Modeling the Semantics of Expression Evaluation with Abstract State Machines.- Extended Abstracts.- Using AsmL for Runtime Verification.- Modeling Information Services on the Basis of ASM Semantics.- Designing the Parlay Call-Control Using ASMs.- Test Case Generation from AsmL Specifications.- Teaching ASMs, Teaching with ASMs: Opportunities in Undergraduate Education.- Using ASM Specifications for Compiler Testing.- ASMs as Integration Platform towards Verification and Validation of Distributed Production Control Systems at Multiple Levels of Abstraction.- AsmL Specification of a Ptolemy II Scheduler.- ASM Specification of Database Systems.- The Computable Kernel of ASM.- A Non-standard Approach to Operational Semantics for Timed Systems.- Parallelism versus Nondeterminism - On the Semantics of Abstract State Machines.

Why Use Evolving Algebras for Hardware and Software Engineering

In this paper I answer the question how evolving algebras can be used for the design and analysis of complex hardware and software systems. I present the salient features of this new method and illustrate them through several examples from my work on specification and verification of programming languages, compilers, protocols and architectures. The definition of a mathematical model for Hennessy and Pattersons RISC architecture DLX serves as a running example; this model is used in [24] to prove the correctness of instruction pipelining. I will point out the yet unexplored potential of the evolving algebra method for large-scale industrial applications.

A mathematical definition of full Prolog

Abstract The paper provides a mathematical yet simple model for the full programming language Prolog, as apparently intended by the ISO draft standard proposal. The model includes all control constructs, database operations, solution collecting predicates and error handling facilities, typically ignored by previous theoretical treatments of the language. We add to this the ubiquitous boxmodel debugger. The model directly reflects the basic intuitions underlying the language and can be used as a primary mathematical definition of Prolog. The core of the model has been applied for mathematical analysis of implementations, for clarification of disputable language features and for specifying extensions of the language in various directions. The model may provide guidance for extending the established theory of logic programming to the extralogical features of Prolog.