Formal verification of language-based concurrent noninterference

We perform a formal analysis of compositionality techniques for proving possibilistic noninterference for a while language with parallel composition. We develop a uniform framework where we express a wide range of noninterference variants from the literature and compare them w.r.t. their contracts: the strength of the security properties they ensure weighed against the harshness of the syntactic conditions they enforce. This results in a simple implementable algorithm for proving that a program has a specific noninterference property, using only compositionality, which captures uniformly several security type-system results from the literature and suggests a further improved type system. All formalism and theorems have been mechanically verified in Isabelle/HOL

Entwicklungstendenzen im österreichischen Wettkampfbodybuilding

Ziel der Arbeit ist es, das Phänomen der Entwicklung der Sportart Bodybuilding, fokussiert auf den österreichischen Leistungssport, aus sportsoziologischer Perspektive zu betrachten. Bodybuilding wird dabei anhand der Luhmannschen Systemtheorie (1984) als funktional differenziertes Sportartensystem betrachtet und mithilfe von Experteninterviews untersucht. Relevante Entwicklungen in der Gesellschaft, sowie der Organisation und Interaktion im Bodybuildingsport können so aufgezeigt werden. Die Trends der Erotisierung, Individualisierung, Technisierung, Extremisierung und Globalisierung werden in ihren Auswirkungen im Bodybuilding nachgewiesen und systemtheoretische Zusammenhänge in der Entwicklung der Sportart aufgezeigt. Die Ausdifferenzierung der Sportart, Demografische Entwicklung, Umgang mit der Dopingthematik und strukturelle Kopplung sind weitere Forschungsschwerpunkte.The objective of this master thesis is to take an in dept look at the sociological approach of sport sciences to the development of bodybuilding, with a focus on bodybuilding as competitive sport in austria. Luhmann’s Systemtheory (1984) is used as a basis to study bodybuilding as a functional differentiated (?) system of sports. Additionally experts on the sport were interviewed. Through this approach it is possible to point out relevant developments in the scoiety, as well as the organization and interaction in bodybuilding. The impact of trends such as erotizisation, individualization, technization, tendencies of extremism and globalization on bodybuilding is demonstrated. Further research focuses were the differentiation of the sport, demographic development, the topic of doping abuse as well as structural linking

Truly modular (co)datatypes for Isabelle/HOL

We extended Isabelle/HOL with a pair of definitional commands for datatypes and codatatypes. They support mutual and nested (co)recursion through well-behaved type constructors, including mixed recursion–corecursion, and are complemented by syntaxes for introducing primitive (co)recursive functions and by a general proof method for reasoning coinductively. As a case study, we ported Isabelle’s Coinductive library to use the new commands, eliminating the need for tedious ad hoc constructions

A Formal Proof of PAC Learnability for Decision Stumps

We present a formal proof in Lean of probably approximately correct (PAC) learnability of the concept class of decision stumps. This classic result in machine learning theory derives a bound on error probabilities for a simple type of classifier. Though such a proof appears simple on paper, analytic and measure-theoretic subtleties arise when carrying it out fully formally. Our proof is structured so as to separate reasoning about deterministic properties of a learning function from proofs of measurability and analysis of probabilities.Comment: 13 pages, appeared in Certified Programs and Proofs (CPP) 202