202,123 research outputs found
A Canonical Locally Named Representation of Binding
No full textThis paper is about completely formal representation of languages with binding. We have previously written about a representation following an approach going back to Frege, based on first-order syntax using distinct syntactic classes for locally bound variables vs. global or free variables (Sato and Pollack, J Symb Comput 45:598–616, 2010). The present paper differs from our previous work by being more abstract. Whereas we previously gave a particular concrete function for canonically choosing the names of binders, here we characterize abstractly the properties required of such a choice function to guarantee canonical representation, and focus on the metatheory of the representation, proving that it is in substitution preserving isomorphism with the nominal Isabelle representation of pure lambda terms. This metatheory is formalized in Isabelle/HOL. The final section outlines a formalization in Matita of a challenging language with multiple binding and simultaneous substitution. The Isabelle and Matita proof files are available online
"Is it Empty? Except for Me..." Sydney Pollack e la American Scene
No full textsaggio sui rapporti tra il cinema di Pollack e la tradizione culturale statunitens
Uncertainty principles connected with the Mobius inversion formula
No full textWe say that two arithmetic functions and form a \emph{M\"{o}bius pair} if for all natural numbers . In that case, can be expressed in terms of by the familiar M\"{o}bius inversion formula of elementary number theory. In a previous paper, the first-named author showed that if the members and of a M\"{o}bius pair are both finitely supported, then both functions vanish identically. Here we prove two significantly stronger versions of this uncertainty principle. A corollary of our results is that in a nonzero M\"{o}bius pair, one cannot have both $\sum_{f(n) \neq 0}\frac{1}{n
Rogers Jewelry - G. M. Pollack and Son, 1975
No full textFull exterior view of Rogers Jewelry - G. M. Pollack and Son store, 549 Congress Street, from south. Lady Grace shop, 547 Congress Street, at right.
Photo published in the Portland Press Herald, on 28 June 1975.https://digitalcommons.portlandlibrary.com/pphnegs_images_business/1173/thumbnail.jp
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On the Fourier-Jacobi Expansion of Quaternionic Modular Forms on Spin(8)
No full textIn this dissertation, we study a class of non-holomorphic, cohomological automorphic functions on the split, simply connected, spin group G=Spin(4,4). Following ideas of Gross-Wallach, Gan-Gross-Savin, M. Weissman, and A. Pollack, we term these automorphic functions quaternionic modular forms on G, and analyze a theory of scalar-valued Fourier coefficients associated to them. Our results build parallels between the theory of quaternionic modular forms on G, and the arithmetically rich theory of genus two Siegel modular forms. The main result states that a level one quaternionic modular form on G is determined by its primitive Fourier coefficients. As an input to this result, we develop a theory of Fourier-Jacobi expansions for quaternionic modular forms, in which the non-degenerate coefficients are themselves genus two Siegel modular forms. Our primary application strengthens earlier joint work of the author with J. Johnson-Leung, I. Negrini, M. Roy, and A. Pollack. More precisely, in this dissertation we show that the level one quaternionic modular forms on SO(4,4) that arise as theta lifts from Sp(4) admit an elementary Fourier coefficient theoretic characterization, which is akin to a characterization of the classical Saito-Kurokawa subspace proven by D. Zagier
A Computational Model of Symbiotic Composition in Evolutionary Transitions
No full textSeveral of the major transitions in evolutionary history, such as the symbiogenic origin of eukaryotes from prokaryotes, share the feature that existing entities became the components of composite entities at a higher level of organisation. This composition of pre-adapted extant entities into a new whole is a fundamentally different source of variation from the gradual accumulation of small random variations, and it has some interesting consequences for issues of evolvability. Intuitively, the pre-adaptation of sets of features in reproductively independent specialists suggests a form of ‘divide and conquer’ decomposition of the adaptive domain. Moreover, the compositions resulting from one level may become the components for compositions at the next level, thus scaling-up the variation mechanism. In this paper, we explore and develop these concepts using a simple abstract model of symbiotic composition to examine its impact on evolvability. To exemplify the adaptive capacity of the composition model, we employ a scale-invariant fitness landscape exhibiting significant ruggedness at all scales. Whilst innovation by mutation and by conventional evolutionary algorithms becomes increasingly more difficult as evolution continues in this landscape, innovation by composition is not impeded as it discovers and assembles component entities through successive hierarchical levels
Embodied Evolution: Distributing an evolutionary algorithm in a population of robots
No full textWe introduce Embodied Evolution (EE) as a new methodology for evolutionary robotics (ER). EE uses a population of physical robots that autonomously reproduce with one another while situated in their task environment. This constitutes a fully distributed evolutionary algorithm embodied in physical robots. Several issues identified by researchers in the evolutionary robotics community as problematic for the development of ER are alleviated by the use of a large number of robots being evaluated in parallel. Particularly, EE avoids the pitfalls of the simulate-and-transfer method and allows the speed-up of evaluation time by utilizing parallelism. The more novel features of EE are that the evolutionary algorithm is entirely decentralized, which makes it inherently scalable to large numbers of robots, and that it uses many robots in a shared task environment, which makes it an interesting platform for future work in collective robotics and Artificial Life. We have built a population of eight robots and successfully implemented the first example of Embodied Evolution by designing a fully decentralized, asynchronous evolutionary algorithm. Controllers evolved by EE outperform a hand-designed controller in a simple application. We introduce our approach and its motivations, detail our implementation and initial results, and discuss the advantages and limitations of EE
Fredi M. Murer, L'âme soeur ; Robert Enrico, Zone Rouge ; Sidney Pollack, Out of Africa (souvenirs d'Afrique)
No full textMalassinet Alain. Fredi M. Murer, L'âme soeur ; Robert Enrico, Zone Rouge ; Sidney Pollack, Out of Africa (souvenirs d'Afrique). In: Raison présente, n°79, 3e trimestre 1986. Approches de la différence. pp. 149-152
Fredi M. Murer, L'âme soeur ; Robert Enrico, Zone Rouge ; Sidney Pollack, Out of Africa (souvenirs d'Afrique)
No full textMalassinet Alain. Fredi M. Murer, L'âme soeur ; Robert Enrico, Zone Rouge ; Sidney Pollack, Out of Africa (souvenirs d'Afrique). In: Raison présente, n°79, 3e trimestre 1986. Approches de la différence. pp. 149-152
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Methods in Cell Biology
No full textThe document titled "Methods in Cell Biology" is a review by Robert E. Pollack, published in The Quarterly Review of Biology in 1976. Pollack provides an evaluation of Volume IX of the "Methods in Cell Biology" series, edited by David M. Prescott. The review highlights the strengths and weaknesses of the volume, which includes 19 articles detailing new techniques in cell biology. Pollack notes that the collection is designed for active research scientists interested in the latest advancements in the field. While he acknowledges the quality of many contributions, particularly in areas like cell synchronization, cell culture, and flow systems for mammalian cells, he also points out some redundancies and organizational issues within the series. Overall, Pollack considers the volume a valuable reference for technical information in cell biology, despite its limitations
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