Tinker, Tailor, Solver, Proof

We introduce Tinker, a tool for designing and evaluating proof strategies based on proof-strategy graphs, a formalism previously introduced by the authors. We represent proof strategies as open-graphs, which are directed graphs with additional input/output edges. Tactics appear as nodes in a graph, and can be `piped' together by adding edges between them. Goals are added to the input edges of such a graph, and flow through the graph as the strategy is evaluated. Properties of the edges ensure that only the right `type' of goals are accepted. In this paper, we detail the Tinker tool and show how it can be integrated with two different theorem provers: Isabelle and ProofPower.Comment: In Proceedings UITP 2014, arXiv:1410.785

A Super Industrial Application of PSGraph

The ClawZ toolset has been successful in verifying that Ada code is correctly generated from Simulink models in an industrial setting, using the Z notation. D-RisQ is now extending this technique to new domains of the C programming language, which requires changes to their highly complex proof technique. In this paper, we present initial results in the technology transfer of the graphical PSGraph language to support this extension, and show feasibility of PSGraph for industrial use with strong maintainability requirements

Thriller, Horror, Hacker, Spy: The Hacker Genre in Film and Television from the 1970s to the 2010s

This thesis argues that hacking and surveillance have formed a ‘hacker’ genre in film and television that begins to emerge from the influences of 1970s films, forming between the 1980s and 1990s and continuing to develop through to the 2010s, grouping together computer hacking, surveillance and espionage as activities striving to achieve order over the ‘electronic frontier’. In particular, this thesis identifies how hacker genre films foreground and fetishise the technology of hacking and surveillance of the period of production, which inevitably leads to an in-built expiry date and limited shelf-life. Whilst these genre films draw on the crime, horror and thriller traditions to depict the tension and anxiety presented by the capabilities of this hacking and surveillance technology, as technology progresses and becomes more familiar to the audience, these films naturally lose their ability to elicit fear and terror from the viewer; instead these films become virtual parodies of their original intention. Moreover, the thesis maps the evolution and development of the generic features of the hacker film genre, charting the progression from passive observation to active intervention of the hacker figure; as the technology progresses, there is an increased sense of speed and mobility and the hacker emerges from small enclosed spaces to engage with the physical world. Similarly, the thesis considers the role of the ‘hacker figure’ in these films, using the viewer’s human connection to consider how this technology affects the user over time; considering the links to the thriller and horror traditions, this study considers the potential for the hacker to become dehumanised in using this technology

Understanding and maintaining tactics graphically OR how we are learning that a diagram can be worth more than 10K LoC

The use of a functional language to implement proof strategies as proof tactics in interactive theorem provers, often provides short, concise and elegant implementations. Whilst being elegant, the use of higher order features and combinator languages often results in a very procedural view of a strategy, which may deviate significantly from the high-level ideas behind it. This can make a tactic hard to understand and hence difficult to to debug and maintain for experts and non-experts alike: one often has to tear apart complex combinations of lower level tactics manually in order to analyse a failure in the overall strategy.In an industrial technology transfer project, we have been working on porting a very large and complex proof tactic into PSGraph, a graphical language for representing proof strategies. The goal of this work is to improve understandability and maintainability of tactics. Motivated by some initial successes with this, we here extend PSGraph with additional features for development and debugging. Through the re-implementation and refactoring of several existing tactics, we demonstrates the advantages of PSGraph compared with a typical sentential tactic language with respect to debugging, readability and maintenance. In order to act as guidance for others, we give a fairly detailed comparison of the user experience with the two approaches. The paper is supported by a web page providing further details about the implementation as well as interactive illustrations of the examples