The Common HOL Platform

The Common HOL project aims to facilitate porting source code and proofs between members of the HOL family of theorem provers. At the heart of the project is the Common HOL Platform, which defines a standard HOL theory and API that aims to be compatible with all HOL systems. So far, HOL Light and hol90 have been adapted for conformance, and HOL Zero was originally developed to conform. In this paper we provide motivation for a platform, give an overview of the Common HOL Platform's theory and API components, and show how to adapt legacy systems. We also report on the platform's successful application in the hand-translation of a few thousand lines of source code from HOL Light to HOL Zero.Comment: In Proceedings PxTP 2015, arXiv:1507.0837

Programmiersprachen und Rechenkonzepte

Die GI-Fachgruppe 2.1.4 "Programmiersprachen und Rechenkonzepte" veranstaltete vom 3. bis 5. Mai 2004 im Physikzentrum Bad Honnef ihren jährlichen Workshop. Dieser Bericht enthält eine Zusammenstellung der Beiträge. Das Treffen diente wie in jedem Jahr gegenseitigem Kennenlernen, der Vertiefung gegenseitiger Kontakte, der Vorstellung neuer Arbeiten und Ergebnisse und vor allem der intensiven Diskussion. Ein breites Spektrum von Beiträgen, von theoretischen Grundlagen über Programmentwicklung, Sprachdesign, Softwaretechnik und Objektorientierung bis hin zur überraschend langen Geschichte der Rechenautomaten seit der Antike bildete ein interessantes und abwechlungsreiches Programm. Unter anderem waren imperative, funktionale und funktional-logische Sprachen, Software/Hardware-Codesign, Semantik, Web-Programmierung und Softwaretechnik, generative Programmierung, Aspekte und formale Testunterstützung Thema. Interessante Beiträge zu diesen und weiteren Themen gaben Anlaß zu Erfahrungsaustausch und Fachgesprächen auch mit den Teilnehmern des zeitgleich im Physikzentrum Bad Honnef stattfindenden Workshops "Reengineering". Allen Teilnehmern möchte ich dafür danken, daß sie mit ihren Vorträgen und konstruktiven Diskussionsbeiträgen zum Gelingen des Workshops beigetragen haben. Dank für die Vielfalt und Qualität der Beiträge gebührt den Autoren. Ein Wort des Dankes gebührt ebenso den Mitarbeitern und der Leitung des Physikzentrums Bad Honnef für die gewohnte angenehme und anregende Atmosphäre und umfassende Betreuung

Church's Thesis and Functional Programming

David Turner's contribution to a volume published on the 70th anniversary of Church's Thesis. ERRATUM: In the published version (Ontos Verlag 2006) Wadsworth's 1976 result on Solvability and head normal form (p6 bottom) was incorrectly attributed to Böhm - this has now been corrected

Be My Guest: Normalizing and Compiling Programs using a Host Language

In programming language research, normalization is a process of fundamental importance to the theory of computing and reasoning about programs.In practice, on the other hand, compilation is a process that transforms programs in a language to machine code, and thus makes the programminglanguage a usable one. In this thesis, we investigate means of normalizing and compiling programs in a language using another language as the "host".Leveraging a host to work with programs of a "guest" language enables reuse of the host\u27s features that would otherwise be strenuous to develop.The specific tools of interest are Normalization by Evaluation and Embedded Domain-Specific Languages, both of which rely on a host language for their purposes. These tools are applied to solve problems in three different domains: to show that exponentials (or closures) can be eliminated from a categorical combinatory calculus, to propose a new proof technique based on normalization for showing noninterference, and to enable the programming of resource-constrained IoT devices from Haskell

Can Computer Programs be Formally Verified?

This paper examines one central problem in the philosophy of computer science, namely the question of whether computer programs can be verified by means of a mathematical proof. Firstly, program verification is defined and the classical debate on its feasibility is recalled under the light of a dual ontology of computational systems. Secondly, the current resurgence of the debate is analysed underlining its logical, technological, and philosophical motivations. Finally, it is shown how adopting a stratified ontology for computational systems one may recombine the different positions in the debate, arguing how program verification involves both deductive and inductive reasoningQuesto articolo esamina il problema, centrale in filosofia dell’informatica, inerente la possibilità di verificare i programmi per calcolatore mediante una dimostrazione matematica. In primo luogo, viene definita la verifica software e viene ricordato il dibattito classico sulla sua possibilità alla luce di una ontologia dualistica dei sistemi computazionali. In secondo luogo, viene analizzato il dibattito attuale sottolineando le motivazioni logiche, tecnologiche e filosofiche del suo rinnovato interesse. Infine, viene mostrato come, adottando un’ontologia stratificata per i sistemi computazionali, si possano ricombinare le diverse posizioni nel dibattito, sostenendo come la verifica software richieda tanto il ragionamento deduttivo quanto quello induttivo