Abstract. Matita is a new, document-centric, tactic-based interactive theorem prover. This paper focuses on some of the distinctive features of the user interaction with Matita, mostly characterized by the organization of the library as a searchable knowledge base, the emphasis on a high-quality notational rendering, and the complex interplay between syntax, presentation, and semantics.

. This paper proposes a set of guidelines for use in the design of automated support for theorem proving. In particular they are aimed at graphical user interfaces to existing interactive proof engines. The application of these guidelines to the design of a graphical user interface to Isabelle is described. 1 Introduction This paper presents a number of principles formulated to guide the design of enhancements to a graphical user interface of an interactive theorem prover. An interactive theorem prover is a tool in which a user chooses and applies proof steps to terms in a given logic, to produce theorems. The prover actually performs the proof steps and ensures that only valid chains of inference are developed. Although there are many standards and texts which provide general guidelines for designing GUIs there is great benefit in attempting to formulate principles and guidelines that are specific to the problem domain of an application. Such specific principles can be informed by th...

This paper presents a model of proof discovery derived from the proof attempts of subjects who carried out interactive proofs using the HOL or Isabelle provers. Techniques of knowledge modelling, from knowledge-basedsystem development, are used to derive a semi-formal model of the knowledge utilised by the subjects. The proposedmodel makes claims about the relation between the problem class, the proof plan and its implementation.

This paper discusses some observations on the differences between what the designers of theorem proving assistants (TPAs) think about the systems they designed and what the users of those TPAs actually find. A questionnaire based on the cognitive dimensions framework was sent to designers and users of a sample of TPAs. The aim of this work is to be able to identify specific areas that designers of TPAs need to devote extra attention to. It was observed that the cognitive dimensions of closeness of mapping, visibility and juxtaposability and perceptual cues are of particular significance.

Abstract. We describe an environment that allows the users of the Theorema system to flexibly control aspects of computer-supported proof development. The environment supports the display and manipulation of proof trees and proof situations, logs the user activities (commands communicated with the system during the proving session), and presents (also unfinished) proofs in a human-oriented style. In particular, the user can navigate through the proof object, expand/remove proof branches, provide witness terms, develop several proofs concurrently, proceed step by step or automatically and so on. The environment enhances the effectiveness and flexibility of the reasoners of the Theorema system. 1

Abstract. This paper presents a model of proof discovery derived from the proof attempts of subjects who carried out interactive proofs using the HOL or Isabelle provers. Techniques of knowledge modelling, from knowledge-basedsystem development, are used to derive a semi-formal model of the knowledge utilised by the subjects. The proposed model makes claims about the relation between the problem class, the proof plan and its implementation. 1

Abstract. Students of proof theory, a branch of formal logic, can benefit from computerized tools. We describe the principles behind one such tool called PROED. This tool is targeted especially at novice students, and therefore it is designed to support effortless exploratory use. We moreover argue that focusing on root-first proof construction in Sequent proof systems helps attain this effortlessness. Key words: logic, user interfaces. 1.

The development of complex, multi-user, interactive systems is a difficult process that requires both a rapid iterative approach, and the ability to reason carefully about system designs. This thesis argues that a combination of declarative prototyping and formal specification provides a suitable way of satisfying these requirements. The focus of this thesis is on the development of software tools for prototyping interactive systems. In particular, it uses a declarative approach, based on the functional programming paradigm. This thesis makes two contributions. The most significant contribution is the presentation of FranTk, a new Graphical User Interface language, embedded in the functional language Haskell. It is suitable for prototyping complex, concurrent, multi-user systems. It allows systems to be built in a high level, structured manner. In particular, it provides good support for specifying real-time properties of such systems. The second contribution is a mechanism that allows a formal specification to be derived from a high level FranTk prototype. The approach allows this to be done automatically. This specification can then be checked, with tool support, to verify some safety properties about a system. To avoid the state space explosion problem that would be faced when verifying an entire system, we focus on partial verification. This concentrates on key areas of a design: in particular this means that we only derive a specification from parts of a prototype. To demonstrate the scalability of both the prototyping and verification approaches, this thesis uses a series of case studies including a multi-user design rationale editor and a prototype data-link