variable assignments x: = e, where e is a-term. The Kleene algebras with tests that arise in this way play a role in dynamic model theory akin to the role played by Lindenbaum algebras in classical rst-order model theory. Given a rst-order theory T over, we exhibit a Kripke frame U whose trace algebra Tr

Scientists need new tools to explore and browse large collections of scholarly literature. Thanks to organizations such as JSTOR, which scan and index the original bound archives of many journals, modern scientists can search digital libraries spanning hundreds of years. A scientist, suddenly

Abstract not found

particular realization of the N = 2 theories, the resulting string field theory is equivalent to a topological theory in six dimensions, the Kodaira– Spencer theory, which may be viewed as the closed string analog of the Chern–Simon theory. Using the mirror map this leads to computation of the ‘number

of some modules. Much of learning involves tuning of these subsymbolic processes. Empirical examples are presented that illustrate the predictions of ACT-R’s modules. In addition, two models of complex tasks are described to illustrate how these modules result in strong predictions when they are brought

Abstract not found

in the Volcker-Greenspan period appears to have been much more sensitive to changes in expected in�ation than in the pre-Volcker period. We then compare some of the implications of the estimated rules for the equilibrium properties of in�ation and output, using a simple macroeconomic model, and show

as follows: ffl We devise a model for dynamic graph algorithms, based on performing queries and updates on an implicit representation of the drawing, and we show its applications. ffl We present several efficient dynamic drawing algorithms for trees, series-parallel digraphs, planar st-digraphs, and planar

We extend earlier ideas about the appearance of noncommutative geometry in string theory with a nonzero B-field. We identify a limit in which the entire string dynamics is described by a minimally coupled (supersymmetric) gauge theory on a noncommutative space, and discuss the corrections away from

of such fundamental notions as objects, classes, and inheritance. Much progress was made by investigating the notion of subtyping within procedural languages and their theoretical models (lambda calculi). These studies clarified the role of subtyping in object-oriented languages, but still relied on complex encodings