KeY is a tool that provides facilities for formal specification and verification of programs within a commercial platform for UML based software development. Using the KeY tool, formal methods and object-oriented development techniques are applied in an integrated manner. Formal specification is performed using the Object Constraint Language (OCL), which is part of the UML standard. KeY provides support for the authoring and formal analysis of OCL constraints. The target language of KeY based development is Java Card DL, a proper subset of Java for smart card applications and embedded systems. KeY uses a dynamic logic for Java Card DL to express proof obligations, and provides a state-of-the-art theorem prover for interactive and automated verification. Apart from its integration into UML based software development, a characteristic feature of KeY is that formal specification and verification can be introduced incrementally.

Many sectors, like finance, medicine, manufacturing, and education, use blockchain applications to profit from the unique bundle of characteristics of this technology. Blockchain technology (BT) promises benefits in trustability, collaboration, organization, identification, credibility, and transparency. In this paper, we conduct an analysis in which we show how open science can benefit from this technology and its properties. For this, we determined the requirements of an open science ecosystem and compared them with the characteristics of BT to prove that the technology suits as an infrastructure. We also review literature and promising blockchain-based projects for open science to describe the current research situation. To this end, we examine the projects in particular for their relevance and contribution to open science and categorize them afterwards according to their primary purpose. Several of them already provide functionalities that can have a positive impact on current research workflows. So, BT offers promising possibilities for its use in science, but why is it then not used on a large-scale in that area? To answer this question, we point out various shortcomings, challenges, unanswered questions, and research potentials that we found in the literature and identified during our analysis. These topics shall serve as starting points for future research to foster the BT for open science and beyond, especially in the long-term.

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Abstract. The KeY system is a development of the ongoing KeY project, whose aim is to integrate formal specification and deductive verification into the industrial software engineering processes. The deductive component of the KeY system is a novel interactive/automated prover for first-order Dynamic Logic for Java. The KeY prover features a user-friendly graphical interface, a backtracking-free free-variable sequent calculus, a simple and powerful theory formalization language called "taclets," solution procedures for linear and non-linear integer arithmetic, external theorem prover integration, and facilities for proof reuse, among other aspects. The system is publicly available.Introduction. The KeY system is the main software product of the KeY project, a joint effort between the University of Karlsruhe, Chalmers University of Technology in Göteborg, and the University of Koblenz. The KeY system is a formal software development tool that aims to integrate design, implementation, formal specification, and formal verification of object-oriented software as seamlessly as possible. At the core of the system is a deductive verification component, which also can be used as a stand-alone prover. It employs a freevariable sequent calculus for first-order Dynamic Logic for JAVA. The calculus is proof-confluent, i.e., no backtracking is necessary during proof search.While we constantly strive to increase the degree of automation, user interaction remains indispensable in deductive program verification. The main design goal of the KeY prover is thus a seamless integration of automated and interactive proving. Efficiency must be measured in terms of user plus prover, not just prover alone. Therefore, a combination of a good user interface for proof state presentation and rule application, a high level of automation, extensibility of the rule base, and a calculus without backtracking is the strong point of KeY.In this paper we concentrate on the description of the KeY prover and the reasoning techniques it employs. The prover consists of ca. 124,000 lines 1 of JAVA code. The standard rule base consists of 1,725 rules that are written in about 15,000 lines of KeY's "taclet" rule description language. About 1,300 of these formalize the semantics of the JAVA programming language. The system has been created by 14 implementors since 1999, who spent a total of about

Abstract. The performance and usability of deductive program verification systems can be greatly enhanced if specifications of programs and program parts not only consist of the usual pre-/post-condition pairs and invariants but also include additional information on which memory locations are changed by executing a program. This allows to separate the aspects of (a) which locations change and (b) how they change, state the change information in a compact way, and make the proof process more efficient. In this paper, we extend this idea from method specifications to loop invariants; and we define a proof rule for while loops that makes use of the change information associated with the loop body. It has been implemented and is successfully used in the KeY software verification system.

Refinement is a well-established and accepted technique for the systematic development of correct software systems. However, for the step from already refined specification to implementation, a correct refinement is often not possible because the data types used in the specification respectively the implementation language differ. In this paper, we discuss this problem and its consequences, using the integer data types of Java as an example, which do not correctly refine the mathematical integers ℤ. We present a solution, which can be seen as a generalisation of refinement and a variant of retrenchment. It has successfully been implemented as part of the KeY software verification system.