William W. Wadge

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Lucid is both a programming language and a formal system for proving properties of Lucid programs. The programming language is unconventional in many ways, although programs are readily understood as using assignment statements and loops in a "structured" fashion. Semantically, an assignment statement is really an equation between "histories", and a whole(More)
We describe a fragment of higher-order Horn logic which can be used as a higher-order extension of Prolog. It allows the programmer to axiomatize predicates of predicates and operations on predicates. The restrictions defining the fragment ensure that the higher-order predicates and operations defined are monotonic and continuous—that they are enumeration(More)
We give a purely model-theoretic characterization of the semantics of logic programs with negation-as-failure allowed in clause bodies. In our semantics, the meaning of a program is, as in the classical case, the unique <i>minimum</i> model in a program-independent ordering. We use an expanded truth domain that has an uncountable linearly ordered set of(More)
We describe an interpreter for pLucid, a member of the Lucid family of functional dataflow languages. In appearance, pLucid is similar to Landin's Iswim, exept that individual variables and expressions denote <i>streams</i> (infinite sequences of data items), and function variables denote <i>filters</i> (stream-to-stream transformations). The actual data(More)
We present a new approach to the control of versions of software and other hierarchically structured entities. Any part of a system, from the smallest component to a complete system, may exist in different versions. The set of all possible versions under the refinement relation forms a partial order (in fact, a lattice). The fact that version V approximates(More)
The purpose of this paper is to demonstrate that rst-order functional programs can be transformed into intensional programs of nullary variables, in a semantics preserving way. On the foundational side, the goal of our study is to bring new insights and a better understanding of the nature of functional languages. From a practical point of view, our(More)
In this paper we propose a novel recommender system which enhances user-based collaborative filtering by using a trust-based social network. Our main idea is to use infinitesimal numbers and polynomials for capturing natural preferences in aggregating opinions of trusted users. We use these opinions to “help” users who are similar to an active user to come(More)