A predicate transformer for the progress property ‘to-always’

The temporal property to-always has been proposed for specifying progress properties of concurrent programs. Although the to-always properties are a subset of the leads-to properties for a given program, to-always has more convenient proof rules and in some cases more accurately describes the desired system behavior. In this paper, we give a predicate transformerwta, derive some of its properties, and use it to define to-always. Proof rules for to-always are derived from the properties ofwta. We conclude by briefly describing two application areas, nondeterministic data flow networks and self-stabilizing systems where to-always properties are useful.     

Structural optimization complexity: what has Moore’s law done for us?

Rapid increases in computer processing power, memory and storage space have not eliminated computational cost and time constraints on the use of structural optimization for design. This is due to the constant increase in the required fidelity (and hence complexity) of analysis models. Anecdotal evidence seems to indicate that analysis models of acceptable accuracy have required at least six to eight hours of computer time (an overnight run) throughout the last thirty years. This poses a severe challenge for global optimization or reliability-based design. In this paper, we review how increases in computer power were utilized in structural optimization. We resolve problem complexity into components relating to complexity of analysis model, analysis procedure and optimization methodology. We explore the structural optimization problems that we can solve at present and conclude that we can solve problems with the highest possible complexity in only two of the three components of model, analysis procedure or optimization. We use examples of optimum design of composite structures to guide the discussion due to our familiarity with such problems. However, these are supplemented with other structural optimization examples to illustrate the universality of the message.     

Global culture, local cultures and the internet: The Thai example

This paper addresses the questions of whether and, if so, how and to what extent the Internet brings about homogenisation of local cultures in the world. It examines a particular case, that of Thai culture, through an investigation and interpretation of a Usenet newsgroup, soc.culture.thai. Two threads of discussion in the newsgroup are selected. One deals with criticisms of the Thai government and political leaders, and the other focuses on whether the Thai language should be a medium, or perhaps the only medium, of communication in the newsgroup. It is found that, instead of erasing local cultural boundaries, creating a worldwide monolithic culture, the Internet reduplicates the existing cultural boundaries. What the Internet does, on the contrary, is to create an umbrella cosmopolitan culture which is necessary for communication among people from disparate cultures. That culture, however, is devoid of thick backgrounds, in Michael Walzer's sense.     

Design and analysis of two-wire focusing actuator for small-sized ODD with linear VCM type’s actuator

Recent advancements in mobile devices have fueled a requirement for information storage systems with characteristics such as subminiature size, low cost, and minimum power consumption. Small optical disk drives could provide a good solution, because their storage media is cheaper than those of hard disk drives or flash memories. In this study, we design and analysis a linear voice coil motor (VCM) types actuator for the coarse and fine tracking motions and a two-wire spring types actuator for a fine focusing motion in order to apply them to small-sized optical disk drives of high data capacity. And, we make the mathematical model of a two-wire spring types actuator and find proper conditions to suppress the tilt motion of the lens holder for various focusing offset positions without sacrificing the sensitivity. Based on them, we design and modify the magnetic circuit and the structural part. Finally, we verify that the designed actuator had the proper dynamic characteristics and that it could be used in small optical disk drives by simulations and experiments.     

Complex-Weighted One-Unit ‘Rigid-Bodies’ Learning Rule for Independent Component Analysis

Over the recent years, noticeable theoretical efforts have been devoted to the understanding of the role of networks' parameter spaces in neural learning. One of the contributions in this field concerns the study of weight-flows on Stiefel manifold, which is the natural parameter-space's algebraic-structure in some unsupervised (information-theoretic) learning task. An algorithm belonging to the class of learning equations generating Stiefel-flows is based on the rigid-body theory, introduced by the present Author in 1996. The aim of this Letter is to present an investigation on the capability of a complex-weighted neuron, trained by a rigid-bodies learning theory, with application to blind source separation of complex-valued independent signals for telecommunication systems.     

Consistency of the Adiabatic Theorem

We review the quantum adiabatic approximation for closed systems, and its recently introduced generalization to open systems (M.S. Sarandy and D.A. Lidar, eprint quant-ph/0404147). We also critically examine a recent argument claiming that there is an inconsistency in the adiabatic theorem for closed quantum systems (K.P. Marzlin and B.C. Sanders, Phys. Rev. Lett. 93, 160408 (2004).) and point out how an incorrect manipulation of the adiabatic theorem may lead one to obtain such an inconsistent result.PACS: 03.65.Ta, 03.65.Yz, 03.67.-a, 03.65.Vf.     

Deterministic polynomial-time quantum algorithms for Simon’s problem

D. R. Simon stated a problem, so-called Simons problem, whose computational complexity is in the class BQP but not in BPP, where is the function or oracle given in the problem. This result indicates that BPP may be strictly included in its quantum counterpart, BQP. Later, G. Brassard and P. Høyer showed that Simons problem and its extended version can be solved by a deterministic polynomial time quantum algorithm. That is, these problems are in the class EQP. In this paper, we show that Simons problem and its extended version can be deterministically solved in a simpler and more concrete way than that proposed by G. Brassard and P. Høyer.     

Optimal shape of a heavy compressed column

By using Pontryagins maximum principle we determine the shape of a heavy compressed rod, stable against buckling. It is assumed that the eigenvalue pair corresponding to the optimal rod is simple. With this assumption (unimodal optimization) it is shown that the cross-sectional area function is determined from the solution of a nonlinear boundary value problem. A variational principle for this boundary value problem is formulated and two first integrals are constructed. The optimal shape of a rod is determined by numerical integration.     

Michell structures formed on surfaces of revolution

The paper formulates the Michell-like problems for surface gridworks. Particular attention is devoted to the problem of designing the lightest fully stressed gridworks formed on surfaces of revolution. In the examples considered, the gridworks are subjected to torsion. Proof is given that the circular meridian is a minimizer of the weight (or volume) functional of a shell subjected to torsion, thus justifying the original Michell conjecture according to which just the spherical twisting shell is the lightest. The proof is based on the methods of the classical variational calculus and thus can be viewed as elementary. This result is confirmed by a direct comparison of the exact formulae for the weight of a spherical Michell shell with the exact formulae for the weights of optimal conical and cylindrical shells with the same fixed boundaries.     

Valiant’s model and the cost of computing integers

Let (n) be the minimum number of arithmetic operations required to build the integer from the constants 1 and 2. A sequence x_n is said to be easy to compute if there exists a polynomial p such that for all It is natural to conjecture that sequences such as or n! are not easy to compute. In this paper we show that a proof of this conjecture for the first sequence would imply a superpolynomial lower bound for the arithmetic circuit size of the permanent polynomial. For the second sequence, a proof would imply a superpolynomial lower bound for the permanent or P PSPACE.     

Dynamics of Lifeboat and Boom in Deployment from a Moving Support

The equations governing the boom-assisted deployment of a lifeboat from a moving support are formulated in three dimensions using Kanes method, accounting for the coupling of the dynamics of the boom and lifeboat. The effect of wind loading is included. At splashdown we assume a controlled water entry and hence the buoyancy force, but not impact force, is modeled. The equations are solved numerically using a standard Runge-Kutta MATLAB routine. Comparison with a known solution for a special case is illustrated.     

The Lagrange problem on an optimal column: old and new results

The paper is devoted to the optimization and post-buckling behavior of columns elastically supported at both ends. The unimodal solutions are analyzed, and it is shown that for nonzero support stiffnesses they are not optimal. The bimodal formulation of the problem is set up. By using analytical expressions for bimodal columns obtained earlier, the bimodal optimal solutions are integrated for different values of the support stiffnesses. With the assumption of geometrical nonlinearity, the post-buckling behavior of the bimodal optimal columns is studied. It is shown that the initial post-buckling behavior is governed by four supercritical solutions emanating from the trivial equilibrium state at the critical load. The stability of the new equilibrium states is investigated by using the second variation of the total potential energy. It is shown that only two post-buckling equilibrium states are stable while the other two are unstable, this conclusion being valid for all considered values of the support stiffnesses. An important limit case of a clamped–simply supported column that has caused debate in many publications is analyzed.     

The π-Calculus in Direct Style

We introduce a calculus which is a direct extension of both the and the calculi. We give a simple type system for it, that encompasses both Curry's type inference for the -calculus, and Milner's sorting for the -calculus as particular cases of typing. We observe that the various continuation passing style transformations for -terms, written in our calculus, actually correspond to encodings already given by Milner and others for evaluation strategies of -terms into the -calculus. Furthermore, the associated sortings correspond to well-known double negation translations on types. Finally we provide an adequate CPS transform from our calculus to the -calculus. This shows that the latter may be regarded as an assembly language, while our calculus seems to provide a better programming notation for higher-order concurrency. We conclude by discussing some alternative design decisions.     

A Platform for Research in Generalization: Application to Caricature

Research on generalization implies a need for intensive experiments with the tools developed. This need implies in turn that a research platform be available which allows for an easy development and integration of new algorithms, and which provides interactive facilities for determining the best tools sequences and tunings with respect to the geometrical characteristics of the features to generalize. We present in this paper such a research platform, named PlaGe, which has been developed from 1992 on and is widely used for shareable research developments in our laboratory. So far, this platform has allowed the research team to implement most of the classical algorithms as well as a technique for segmenting and characterizing line features. It is worth noting that this latter point is of prime importance in order to be able to apply the right processing with respect to the local geometry. To automate further the generalization process, starting with the currently available set of algortihms for simplification and smoothing, requires the investigation of two complementary issues: devising algorithmical implementations for operators such as caricature and schematization, which are often needed to cope with complex geometries, and determining a generalization strategy which, on the basis of computed geometrical characteristics, results in the application of the best sequences. Four new algorithms, for caricature and schematization, are introduced in the following, as well as a generalization strategy. The results obtained so far indicate that we should be able to automate significantly the generalization process for practical production needs.     

A Typology of Translation Problems for Eurotra Translation Machines

This paper presents a detailed study of Eurotra Machine Translation engines, namely the mainstream Eurotra software known as the E-Framework, and two unofficial spin-offs – the C,A,T and Relaxed Compositionality translator notations – with regard to how these systems handle hard cases, and in particular their ability to handle combinations of such problems. In the C,A,T translator notation, some cases of complex transfer are wild, meaning roughly that they interact badly when presented with other complex cases in the same sentence. The effect of this is that each combination of a wild case and another complex case needs ad hoc treatment. The E-Framework is the same as the C,A,T notation in this respect. In general, the E-Framework is equivalent to the C,A,T notation for the task of transfer. The Relaxed Compositionality translator notation is able to handle each wild case (bar one exception) with a single rule even where it appears in the same sentence as other complex cases.     

A Mathematical Analysis of Pānini’s <Emphasis Type="Italic">Śivasūtras</Emphasis>

In Pninis grammar of Sanskrit one finds the ivastras, a table which defines the natural classes of phonological segments in Sanskrit by intervals. We present a formal argument which shows that, using his representation method, Pninis way of ordering the phonological segments to represent the natural classes is optimal. The argument is based on a strictly set-theoretical point of view depending only on the set of natural classes and does not explicitly take into account the phonological features of the segments, which are, however, implicitly given in the way a language clusters its phonological inventory. The key idea is to link the graph of the Hasse-diagram of the set of natural classes closed under intersection to ivastra-style representations of the classes. Moreover, the argument is so general that it allows one to decide for each set of sets whether it can be represented with Pninis method. Actually, Pnini had to modify the set of natural classes to define it by the ivastras (the segment h plays a special role). We show that this modification was necessary and, in fact, the best possible modification. We discuss how every set of classes can be modified in such a way that it can be defined in a ivastra-style representation.¹     

Automatic surface reconstruction with alpha-shape method

In this paper, we present an algorithm for the reconstruction of piecewise linear surfaces from unorganized sample points with an improved -shape. Alpha-shape provides a nice mathematical definition of the shape of a set of points, but the selection of an value is tricky in surface reconstruction. F or solving this problem and the non-uniform distribution, we scale the ball according to the points density. The method discussed in this paper might be applied for surface reconstruction, and the process is fully automatic.