24,752 research outputs found
Actions and Events in Concurrent Systems Design
In this work, having in mind the construction of concurrent systems from
components, we discuss the difference between actions and events. For this
discussion, we propose an(other) architecture description language in which
actions and events are made explicit in the description of a component and a
system. Our work builds from the ideas set forth by the categorical approach to
the construction of software based systems from components advocated by Goguen
and Burstall, in the context of institutions, and by Fiadeiro and Maibaum, in
the context of temporal logic. In this context, we formalize a notion of a
component as an element of an indexed category and we elicit a notion of a
morphism between components as morphisms of this category. Moreover, we
elaborate on how this formalization captures, in a convenient manner, the
underlying structure of a component and the basic interaction mechanisms for
putting components together. Further, we advance some ideas on how certain
matters related to the openness and the compositionality of a component/system
may be described in terms of classes of morphisms, thus potentially supporting
a compositional rely/guarantee reasoning.Comment: In Proceedings LAFM 2013, arXiv:1401.056
A Formalization of the Theorem of Existence of First-Order Most General Unifiers
This work presents a formalization of the theorem of existence of most
general unifiers in first-order signatures in the higher-order proof assistant
PVS. The distinguishing feature of this formalization is that it remains close
to the textbook proofs that are based on proving the correctness of the
well-known Robinson's first-order unification algorithm. The formalization was
applied inside a PVS development for term rewriting systems that provides a
complete formalization of the Knuth-Bendix Critical Pair theorem, among other
relevant theorems of the theory of rewriting. In addition, the formalization
methodology has been proved of practical use in order to verify the correctness
of unification algorithms in the style of the original Robinson's unification
algorithm.Comment: In Proceedings LSFA 2011, arXiv:1203.542
Designing Normative Theories for Ethical and Legal Reasoning: LogiKEy Framework, Methodology, and Tool Support
A framework and methodology---termed LogiKEy---for the design and engineering
of ethical reasoners, normative theories and deontic logics is presented. The
overall motivation is the development of suitable means for the control and
governance of intelligent autonomous systems. LogiKEy's unifying formal
framework is based on semantical embeddings of deontic logics, logic
combinations and ethico-legal domain theories in expressive classic
higher-order logic (HOL). This meta-logical approach enables the provision of
powerful tool support in LogiKEy: off-the-shelf theorem provers and model
finders for HOL are assisting the LogiKEy designer of ethical intelligent
agents to flexibly experiment with underlying logics and their combinations,
with ethico-legal domain theories, and with concrete examples---all at the same
time. Continuous improvements of these off-the-shelf provers, without further
ado, leverage the reasoning performance in LogiKEy. Case studies, in which the
LogiKEy framework and methodology has been applied and tested, give evidence
that HOL's undecidability often does not hinder efficient experimentation.Comment: 50 pages; 10 figure
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