Effective Interactive Proofs for Higher-Order Imperative Programs

We present a new approach for constructing and verifying higher-order, imperative programs using the Coq proof assistant. We build on the past work on the Ynot system, which is based on Hoare Type Theory. That original system was a proof of concept, where every program verification was accomplished via laborious manual proofs, with much code devoted to uninteresting low-level details. In this paper, we present a re-implementation of Ynot which makes it possible to implement fully-verified, higher-order imperative programs with reasonable proof burden. At the same time, our new system is implemented entirely in Coq source files, showcasing the versatility of that proof assistant as a platform for research on language design and verification. Both versions of the system have been evaluated with case studies in the verification of imperative data structures, such as hash tables with higher-order iterators. The verification burden in our new system is reduced by at least an order of magnitude compared to the old system, by replacing manual proof with automation. The core of the automation is a simplification procedure for implications in higher-order separation logic, with hooks that allow programmers to add domain-specific simplification rules. We argue for the effectiveness of our infrastructure by verifying a number of data structures and a packrat parser, and we compare to similar efforts within other projects. Compared to competing approaches to data structure verification, our system includes much less code that must be trusted; namely, about a hundred lines of Coq code defining a program logic. All of our theorems and decision procedures have or build machine-checkable correctness proofs from first principles, removing opportunities for tool bugs to create faulty verifications.Engineering and Applied Science

Securing Cross-App Interactions in IoT Platforms

IoT platforms enable users connect various smart devices and online services via reactive apps running on the cloud. These apps, often developed by third-parties, perform simple computations on data triggered by external information sources and actuate the results of computation on external information sinks. Recent research shows that unintended or malicious interactions between the different (even benign) apps of a user can cause severe security and safety risks. These works leverage program analysis techniques to build tools for unveiling unexpected interference across apps for specific use cases. Despite these initial efforts, we are still lacking a semantic framework for understanding interactions between IoT apps. The question of what security policy cross-app interference embodies remains largely unexplored. This paper proposes a semantic framework capturing the essence of cross-app interactions in IoT platforms. The frame- work generalizes and connects syntactic enforcement mechanisms to bisimulation-based notions of security, thus providing a baseline for formulating soundness criteria of these enforcement mechanisms. Specifically, we present a calculus that models the behavioral semantics of a system of apps executing concurrently, and use it to define desirable semantic policies in the context security and safety of IoT apps. To demonstrate the usefulness of our framework, we define static mechanisms for enforcing cross- app security and safety, and prove them sound with respect to our semantic conditions. Finally, we leverage real-world apps to validate the practical benefits of our policy framework

Prolegomena To The Automated Analysis Of A Bilingual Poetry Corpus, With Particular Reference To An Annotated Edition Of “the Cantos” Of Ezra Pound

Standing at the intersection of a theoretical investigation into the possibilities of applying the tools and methods of automated analysis to a large plurilingual poetry corpus and of a set of observables gleaned along the creation of a digitally annotated edition of The Cantos of Ezra Pound — a robust test-case for the TEI — the present dissertation can be read under different guises. One of them, for instance, would be that of a comedy, divina commedia or com�dia de Deus, in which the computer plays — Leibnizian harmonics! — the part of supreme intellect. A: The selva oscura is that of newly born “Digital Humanities” — burgeoning yet obscured already by two dominant paradigms. On the one hand, the constructivism inherited from poststructuralist theory; on the other, a na�ve return to the most trivial kind of linguistic realism. There, the literary text is construed as an object of absolute singularity, transcending any possible analysis based on explicit methods; here, it becomes a mere point in a network of quodities. Literariness is gone. The second circle revolves around a singular, and singularly marked, exemple of antinomian discourse — the concomitant use of the notions of error and genius in respect to The Cantos — the uniqueness of the modernist project supposed to defeat all generalizing claims made by philology. Alas, facts are stubborn things; so are mistakes. These must be corrected, but on what grounds? We plead for the necessity of a genetic — a digital genetic — edition, which only can transcend the arbitrary organizational imperialism of standard sheets of paper. B. The purgatory of labor, the attempts to analyze the text without betraying its intricacies. What is a line? What is a proper name? What is a quotation? The path is steep, but the air starts to clear up. C. Ascension — Love supreme — Paradise in sight: the realm of results. Through graphs, colors appear, in the stead of black ink on white paper — beautifully, but oh so fleetingly

(Dis)Obedience in Digital Societies: Perspectives on the Power of Algorithms and Data

Algorithms are not to be regarded as a technical structure but as a social phenomenon - they embed themselves, currently still very subtle, into our political and social system. Algorithms shape human behavior on various levels: they influence not only the aesthetic reception of the world but also the well-being and social interaction of their users. They act and intervene in a political and social context. As algorithms influence individual behavior in these social and political situations, their power should be the subject of critical discourse - or even lead to active disobedience and to the need for appropriate tools and methods which can be used to break the algorithmic power

(Dis)Obedience in Digital Societies

Algorithms are not to be regarded as a technical structure but as a social phenomenon - they embed themselves, currently still very subtle, into our political and social system. Algorithms shape human behavior on various levels: they influence not only the aesthetic reception of the world but also the well-being and social interaction of their users. They act and intervene in a political and social context. As algorithms influence individual behavior in these social and political situations, their power should be the subject of critical discourse - or even lead to active disobedience and to the need for appropriate tools and methods which can be used to break the algorithmic power

Tacit knowledge in craft pedagogy: a sociological analysis

Though a very silent man he was so mild and calm that Ged soon lost his awe of him, and in a day or two he was bold enough to ask his master 'When will my apprenticeship begin, Sir?' 'It has begun', said Ogion. There was silence, as if Ged was keeping back something he had to say. Then he said it: 'But I haven't learned anything yet!' 'Because you haven't found out what I am teaching,' replied the mage. going on at his steady long-legged pace along their road ... From: The Earthsea Quartet, by Ursula /e Guin This thesis explores the relationship between tacit knowledge and a pedagogy that centres round a master-apprentice relationship, in order to locate tacit craft knowledge within a broader taxonomy of knowledge forms and their transmission practices. By its own definition tacit knowledge constitutes a unique class of phenomenon, namely that which is not presentable in language. It is thus a difficult concept to grasp and an even more difficult concept to represent in words. Evidence from a single qualitative case study on craft transmission practices m the institutional training centre of the Furniture Industry Training Board (known as the 'trade school') in Cape Town is presented and analysed in accordance with a conceptual scheme that derives from the earlier work of Basil Bernstein. Against the background of this analysis of craft pedagogy, the nature of the 'tacit' is explored through a detailed analysis of the evaluative requirements of the final trade test. Thereafter a conceptual model is developed to provide a theoretical explanation for the form that tacit craft knowledge takes. The findings show that strong external 'classification' and 'framing' relations (terms developed by Bernstein) constitute the trade school as a specialised context that is temporarily insulated from the work practices of mass production factories. It is a particular relation between work organisation, tool and materials usage, that retains the traditional craft or trade of cabinet making as the 'identity' recognised as legitimate in the trade school. Internal 'framing' displays two modalities. While strong macro pacing that resembles the daily routine in a factory is maintained throughout the five stages of the apprenticeship II curriculum, very weak initial framing over selection, sequencing and mtcro pacing allows apprentices to develop their own rhythms of work and to make their own decisions about task realisation. However, just before the end of the final stage and before apprentices take their final trade test framing over selection, sequencing and pacing is strengthened and made explicit. Evaluation criteria are very strongly framed in all stages of the apprenticeship curriculum. In terms of the regulative discourse of the trade school the master-apprentice relation is undoubtedly an asymmetrical relation that is mediated through a surrogate kinship role taken on by the master-trainer to exercise a form of positional control. The qualities of character and conduct that are transmitted are those of the autonomous artisan representing a collective craft tradition. The outcome of a strongly classified and framed craft pedagogy that centres round a masterapprentice relationship is found to be an external performance that is grounded or embedded in an internally held competence. Such internalised competence refers to a capacity for visualisation that acts as a proxy for a relationship between 'parts' and 'whole' that cannot be rendered in words. This relationship is held in the body and constitutes what can be called the 'tacit' in craft. The identity of the craft worker or 'tradesman' rests crucially on this combination of external performance and internalised time-space relation. Given this understanding of craft it becomes possible to describe craft as a restricted form of context independent 'knowledge' rather than merely as 'skill'. The conceptual model that is developed in the later part of the thesis locates craft as a form of knowledge that is independent of context in the sense that all craft knowledge realises an order of relation between the features of the object being made that is given by a particular embodied principle of arrangement. It is on this basis that craft takes its place in a systematic taxonomy of knowledge forms, which, although functioning at a fairly high level of abstraction 1s, nevertheless consistent with the empirical findings of the study. Implications of thesis findings and conclusions for an understanding of knowledge and pedagogy more generally are presented in the final chapter