Optimal control systems with time delay and conditions for normality

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Conjugacy for normal or abnormal linear Bolza problems

AbstractFor certain Bolza problems with linear dynamics, two sets extending the notion of conjugate points in the calculus of variations are introduced. Independently of nonsingularity assumptions, their emptiness, in one case without normality assumptions, is shown to be equivalent to a second order necessary condition. A comparison with other notions available in the literature is given

Geotechnical Lessons Learned from Mexico and Other Recent Earthquakes

This paper describes the most relevant effects of the September 1985 earthquakes on Mexico City. It discusses the results of recent exploration and research on regional geology, local site conditions and site response analyses, basic soil properties, and observation of actual behavior of soil-foundation-structure systems. The paper shows the impact of these investigations upon new - building code requirements, on general design practice and on the specialist\u27s perception of earthquake behavior of Mexico City\u27s subsoil. Recent earthquakes recorded in and around Mexico City have contributed insight into some of the unresolved questions left after the experience of 1985. Damaging earthquakes recorded in other cities in the near past are brought into the discussion. The latter events furnish- by means of the examples of San Salvador in 1986, Armenia in 1988 and San Francisco in 1989 - more general view of the influence of local subsoil conditions on site response

SLR inference: An inference system for fixed-mode logic programs, based on SLR parsing

AbstractDefinite-clause grammars (DCGs) generalize context-free grammars in such a way that Prolog can be used as a parser in the presence of context-sensitive information. Prolog's proof procedure, however, is based on backtracking, which may be a source of inefficiency. Parsers for context-free grammars that use backtracking, for instance, were soon replaced by more efficient methods, such as LR parsers. This suggests incorporating the principles underlying LR parsing into a parser for grammars with context-sensitive information. We present a technique that applies a transformation to the program/grammar by adding leaves to the proof/parse trees and placing the contextual information in such leaves. An inference system is then easily obtained from an LR parser, since only the parts dealing with terminals (which appear at the leaves) must be modified. Although our method is restricted to programs with fixed modes, it may be preferable to DCGs under Prolog for some programs