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Journals and Conferences
The set of binary trees together with the homeomorphic embedding build an wellpartial-ordering. It is well known that its maximal order type is ε0 as shown by de Jongh and that its canonical linearization is the system obtained from the celebrated Feferman-Schütte system for Γ0 by omitting the addition operator. We show here that Higman’s Lemma and… (More)
This paper presents GMeta: a generic framework for firstorder representations of variable binding that provides once and for all many of the so-called infrastructure lemmas and definitions required in mechanizations of formal metatheory. The key idea is to employ datatypegeneric programming (DGP) and modular programming techniques to deal with the… (More)
We compute the sharp thresholds on g at which g-large and g-regressive Ramsey numbers cease to be primitive recursive and become Ackermannian. We also identify the threshold below which g-regressive colorings have usual Ramsey numbers, that is, admit homogeneous, rather than just min-homogeneous sets.
We introduce a notion of Kripke model for classical logic for which we constructively prove soundness and cut-free completeness. We discuss the novelty of the notion and its potential applications.
We give a simple intuitionistic completeness proof of Kripke semantics with constant domain for intuitionistic logic with implication and universal quantification. We use a cut-free intuitionistic sequent calculus as formal system and by combining soundness with completeness, we obtain an executable cut-elimination procedure. The proof, which has been… (More)
We present a set-theoretic, proof-irrelevant model for Calculus of Constructions (CC) with predicative induction and judgmental equality in Zermelo-Fraenkel set theory with an axiom for countably many inaccessible cardinals. We use Aczel’s trace encoding which is universally defined for any function type, regardless of being impredicative. Direct and… (More)
The f -regressive Ramsey number R f (d, n) is the minimum N such that every colouring of the d-tuples of an N -element set mapping each x1, . . . , xd to a colour ≤ f(x1) contains a min-homogeneous set of size n, where a set is called min-homogeneous if every two d-tuples from this set that have the same smallest element get the same colour. If f is the… (More)
In an overview paper called State of the Art: Embedding Security in Vehicles, Wolf et al. give a general stateof- the-art overview of IT security in vehicles and describe core security technologies and relevant security mechanisms. In this paper we show that a formal analysis of many of the related properties is possible. This indicates that many expected… (More)
When mechanizing the metatheory of a programming language, one usually needs many lemmas proving structural properties of typing judgments, such as permutation and weakening. Such structural lemmas are sometimes unnecessary if we eliminate typing contexts by expanding typing judgments into their original hypothetical proofs. This technique of eliminating… (More)
Concerning the set of rooted binary trees, one shows that Higman’s Lemma and Dershowitz’s recursive path ordering can be used for the decision of its maximal order type according to the homeomorphic embedding relation as well as of the order type according to its canonical linearization, well-known in proof theory as the Feferman-Schütte notation system… (More)