No Arabic abstract
Designing software that controls industrial equipment is challenging, especially due to its inherent concurrent nature. Testing this kind of event driven control software is difficult and, due to the large number of possible execution scenarios only a low dynamic test coverage is achieved in practice. This in turn is undesirable due to the high cost of software failure for this type of equipment. In this paper we describe the Dezyne language and tooling; Dezyne is a programming language aimed at software engineers designing large industrial control software. We discuss its underlying two layered and compositional approach that enables reaping the benefits of Formal Methods, hereby strongly supporting guiding principles of software engineering. The core of Dezyne uses the mCRL2 language and model-checker (Jan Friso Groote et al.) to verify the correctness and completeness of all possible execution scenarios. The IDE of Dezyne is based on the Language Server Protocol allowing a smooth integration with e.g., Visual Studio Code, and Emacs, extended with several automatically generated interactive graphical views. We report on the introduction of Dezyne and its predecessor at several large high-tech equipment manufacturers resulting in a decrease of software developing time and a major decrease of reported field defects.
Development of formal proofs of correctness of programs can increase actual and perceived reliability and facilitate better understanding of program specifications and their underlying assumptions. Tools supporting such development have been available for over 40 years, but have only recently seen wide practical use. Projects based on construction of machine-checked formal proofs are now reaching an unprecedented scale, comparable to large software projects, which leads to new challenges in proof development and maintenance. Despite its increasing importance, the field of proof engineering is seldom considered in its own right; related theories, techniques, and tools span many fields and venues. This survey of the literature presents a holistic understanding of proof engineering for program correctness, covering impact in practice, foundations, proof automation, proof organization, and practical proof development.
In this extended abstract a view on the role of Formal Methods in System Engineering is briefly presented. Then two examples of useful analysis techniques based on solid mathematical theories are discussed as well as the software tools which have been built for supporting such techniques. The first technique is Scalable Approximated Population DTMC Model-checking. The second one is Spatial Model-checking for Closure Spaces. Both techniques have been developed in the context of the EU funded project QUANTICOL.
The FermaT transformation system, based on research carried out over the last sixteen years at Durham University, De Montfort University and Software Migrations Ltd., is an industrial-strength formal transformation engine with many applications in program comprehension and language migration. This paper is a case study which uses automated plus manually-directed transformations and abstractions to convert an IBM 370 Assembler code program into a very high-level abstract specification.
The optimization phase of a compiler is responsible for transforming an intermediate representation (IR) of a program into a more efficient form. Modern optimizers, such as that used in the GraalVM compiler, use an IR consisting of a sophisticated graph data structure that combines data flow and control flow into the one structure. As part of a wider project on the verification of optimization passes of GraalVM, this paper describes a semantics for its IR within Isabelle/HOL. The semantics consists of a big-step operational semantics for data nodes (which are represented in a graph-based static single assignment (SSA) form) and a small-step operational semantics for handling control flow including heap-based reads and writes, exceptions, and method calls. We have proved a suite of canonicalization optimizations and conditional elimination optimizations with respect to the semantics.
In this paper we introduce the notion of Modal Software Engineering: automatically turning sequential, deterministic programs into semantically equivalent programs efficiently operating on inputs coming from multiple overlapping worlds. We are drawing an analogy between modal logics, and software application domains where multiple sets of inputs (multiple worlds) need to be processed efficiently. Typically those sets highly overlap, so processing them independently would involve a lot of redundancy, resulting in lower performance, and in many cases intractability. Three application domains are presented: reasoning about feature-based variability of Software Product Lines (SPLs), probabilistic programming, and approximate programming.