3 Logical Relation Proofs 15 3.1 Basic Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 3.1.1 Properties of Step-Indexed Construction . . . . . . . . . . . . . . . . . . . . . . . . . . 15 3.1.2 Approximation Yields Valid Semantic Objects . . . . . . . . . . . . . . . . . . . . . . 17 3.1.3 World Extension and Store Satisfaction Properties . . ...

We provide a very simple model of a reeective facility based on the pure-calculus, and we show that its theory of contextual equivalence is trivial: two terms in the language are contextually equivalent ii they are-congruent.

Privacy related properties in electronic voting are naturally expressed as indistinguishability properties. This motivates the study of observational equivalence, as well as static equivalence in the context of the AVOTÉ project. In this report we survey the existing results on the computational soundness of symbolic indistinguishability relations in the presence of a passive adversary, for whi...

In this note, we present a proof of Π2-completeness of contextual equivalence of Turing machines via a reduction of the language FIN to contextual inequivalence. FIN is the language of encodings 〈Mi〉 of Turing machines Mi for which the set Wi of inputs on which Mi halts (or the set of accepting inputs of Mi) is finite. FIN is known to be Σ 0 2-complete.

This study was an unobtrusive observational analysis of 333 older and younger bus passengers in Guadalajara, Mexico. A set of data were collected for each observed passenger, as well as more general observations related to driver behaviour, bus design and bus service characteristics. There were significant differences between older and younger passengers in terms of boarding and alighting times...

There are results which show that measure-theoretic deterministic models and stochastic models are observationally equivalent. Thus there is a choice between a deterministic and an indeterministic model and the question arises: Which model is preferable relative to evidence? If the evidence equally supports both models, there is underdetermination. This paper first distinguishes between differe...

This paper presents and philosophically assesses three types of results on the observational equivalence of continuous-time measure-theoretic deterministic and indeterministic descriptions. The first results establish observational equivalence to abstract mathematical descriptions. The second results are stronger because they show observational equivalence between deterministic and indeterminis...

Subtyping in first order object calculi is studied with respect to the logical semantics obtained by identifying terms that satisfy the same set of predicates, as formalized through an assignment system. It is shown that equality in the full first order ς-calculus is modelled by this notion, which on turn is included in a Morris style contextual equivalence.