Fairness in context-free grammars under every choice-strategy

In (Porat et al., 1982, Inform. and Control 55, 108–116) the notion of fair derivations in context-free grammars was introduced and studied. The main result there is a characterization of fairly terminating grammars as non-variable-doubling. In this paper we show that the same characterization is valid under canonical derivations in which the next variable to be expanded is deterministically chosen, leaving nondeterminism only to the decision as to which rule (of the chosen variable) to apply. Two families of canonical derivations are introduced and studied as special cases: spinal derivations and layered derivations.     

Fast set intersection and two-patterns matching

In this paper we present a new problem, the fast set intersection problem, which is to preprocess a collection of sets in order to efficiently report the intersection of any two sets in the collection. In addition we suggest new solutions for the two-dimensional substring indexing problem and the document listing problem for two patterns by reduction to the fast set intersection problem.     

Simplified Analytical Treatment of Defect Equilibria: Applications to Oxides with Multivalent Dopants

A simplified analytical treatment of rather complex defect equilibria involving systems with multivalent dopants is presented. This approach is first demonstrated for the case of Gd₂Ti₂O₇; doped with multiple valent donors, in which the effects of variations in donor ionization levels and in the equilibrium constants on the defect equilibria are examined. The conductivity data of U doped CeO₂ are then evaluated, leading to equilibrium constants in good agreement with previous results, but allowing a more complete analysis.     

Aroma volatile compositions of high- and low-aromatic guava varieties

BACKGROUND: The traditional guava variety cultivated in Israel, ‘Ben Dov’, emits a very strong odour, whereas some newly bred varieties have a mild odour. In this study the aroma profile composition of the high‐aromatic ‘Ben Dov’ variety was compared with those of four new low‐aromatic varieties. RESULTS: Overall, using gas chromatography/mass spectrometry, a total of 30 aroma volatiles were detected in fresh ripe guava fruit: 15 of them were specifically detected only in the high‐aromatic ‘Ben Dov’ variety, 13 were detected in both the high‐ and low‐aromatic varieties and two were detected only in the new low‐aromatic varieties. Interestingly, 11 out of the 15 volatiles specifically detected in ‘Ben Dov’ were esters that contribute sweet, tropical and fruity notes. In contrast, ten out of 13 detected terpenes and two detected aldehydes, contributing green, spicy, herbal and woody notes, were common to both the high‐ and low‐aromatic varieties. CONCLUSION: Based on these findings, it is concluded that accumulation of esters is the main reason why the traditional ‘Ben Dov’ guava variety emits such a strong tropical fruity odour. In contrast, the newly bred low‐aromatic guava varieties did not synthesise esters at all and thus lacked fruity aromatic notes. Overall, the results of this study point out the important role of esters in forming tropical fruity guava odours. Copyright © 2011 Society of Chemical Industry     

Optimal reconstruction of images from localized phase

The importance of localized phase in signal representation is investigated. The convergence rate of the POCS algorithm (projection onto convex sets) used for image reconstruction from spectral phase is defined and analyzed, and the characteristics of images optimally reconstructed from phase-only information are presented. It is concluded that images of geometric form are most efficiently reconstructed from their spectral phase, whereas images of symmetric form have the poorest convergence characteristics. The transition between the two extremes is shown to be continuous. The results provide a new approach and analysis of the previously reported advantages of the localized phase representation over the global approach, and suggest possible compression schemes.     

On the generalized likelihood ratio test for a class of nonlineardetection problems

The authors examine the generalized likelihood ratio test (GLRT) for a certain class of detection problems. This class is characterized by a model which is linear in some parameters and nonlinear in others. They show that the classical asymptotic analysis of the GLRT fails for this class, and demonstrate the existence of ill-behaved cases in this class. They then propose a modification of the GLRT. The main advantage of this modification is that its probability of false-alarm is easily computable, thus facilitating the choice of threshold according to the Neyman-Pearson criterion. Performance analysis of the modified GLRT is provided and supported by simulations     

Estimation of Pr{X>Y} or Pr{X⩽Y}

The paper presents a procedure for the estimation (point and interval) for a reliability model of the form Pr{X>Y} or Pr{X⩽Y} and Gaussian (normal) distributed variables. The procedures are derived from a quantitative approach that allows the user to get sufficient evidence, concerning the product reliability, by testing a small sample but at severe conditions, rather than testing a large sample at the nominal working conditions. Y has known parameters while X is a Gaussian r.v. with an unknown mean and a known coefficient-of-variation. The procedure is practical and cost effective when facing situations such as high test-cost, or severe contractual reliability requirements     

SOME ASYMPTOTIC PROPERTIES OF THE SAMPLE COVARIANCES OF GAUSSIAN AUTOREGRESSIVE MOVING-AVERAGE PROCESSES

Abstract. The paper deals with the asymptotic variances of the sample covariances of autoregressive moving average processes. Using state-space representations and some matrix Lyapunov equation theory, closed-form expressions are derived for the asymptotic variances of the sample covariances and for the Cramer-Rao bounds on the process covariances. The main results obtained from these expressions are as follows: For ARMA ( p, q ) processes with p ≥ q , the sample covariance of order n is asymptotically efficient if and only if 0 ≤ n ≤ p – q .
For ARMA ( p, q ) processes with p < q , none of the sample covariances is asymptotically efficient.     

Global Implications of the Information Society

"As with life itself, the prognosis for an information society is mixed, the remedy inconclusive."