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41,464
OPT
"... Let X = f1; 2; : : : ; ng be a ground set of n elements, and let S be a family of subsets of X, jSj = m, with a positive cost c S associated with each S 2 S. Consider the following online version of the set cover problem, described as a game between an algorithm and an adversary. An adversary gives ..."
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Let X = f1; 2; : : : ; ng be a ground set of n elements, and let S be a family of subsets of X, jSj = m, with a positive cost c S associated with each S 2 S. Consider the following online version of the set cover problem, described as a game between an algorithm and an adversary. An adversary gives elements to the algorithm from X onebyone. Once a new element is given, the algorithm has to cover it by some set of S containing it. We assume that the elements of X and the members of S are known in advance to the algorithm, however, the set X 0 X of elements given by the adversary is not known in advance to the algorithm. (In general, X 0 may be a strict subset of X.) The objective is to minimize the total cost of the sets chosen by the algorithm. Let C denote the family of sets in S that the algorithm chooses. At the end of the game the adversary also produces (oline) a family of sets C
OPT
"... The classical response spectrum method (RSM) was developed in 1932 for excitation by synchronous ground motion at all supports. It is shown in this paper how RSM can be generalized to the analyses of extended structures, (1) experiencing differential inplane, and outofplane ground motions, and (2 ..."
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The classical response spectrum method (RSM) was developed in 1932 for excitation by synchronous ground motion at all supports. It is shown in this paper how RSM can be generalized to the analyses of extended structures, (1) experiencing differential inplane, and outofplane ground motions, and (2) crossing active faults. A relative displacement spectrum for design of bridge columns, or of firststory columns in buildings, SDC (T, TT, ζ, ζT, τ), is defined. In addition to the natural periods of the inplane response, , and of the outofplane response, , such that, and the corresponding fractions of critical damping,
Methodo log ica l and Ideo log ica l Opt ions Preferences, information and biodiversity preservation
, 1993
"... This paper considers the nature of preferences for the preservation of biodiversity, and the extent to which individuals are wellinformed about biodiversity. We present evidence that the elicitation of monetary bids to pay for biodiversity preservation, as required for costbenefit analysis, fails ..."
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This paper considers the nature of preferences for the preservation of biodiversity, and the extent to which individuals are wellinformed about biodiversity. We present evidence that the elicitation of monetary bids to pay for biodiversity preservation, as required for costbenefit analysis, fails as a measure of welfare changes due to the prevalence of preferences which neoclassical economics defines as lexicographic. That is, a significant proportion of individuals refuse to make tradeoffs which require the substitution of biodiversity for other goods. In addition, we show that understanding of the biodiversity concept is extremely limited, raising concerns over a reliance on stated preferences, as revealed in contingent valuation studies, for decisionmaking on this issue. Results from two samples (students and the general public) are described.
A Recursive Greedy Algorithm for Walks in Directed Graphs
 PROC. OF IEEE FOCS
, 2005
"... Given an arcweighted directed graph G = (V, A, ℓ) and a pair of nodes s, t, we seek to find an st walk of length at most B that maximizes some given function f of the set of nodes visited by the walk. The simplest case is when we seek to maximize the number of nodes visited: this is called the ori ..."
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Cited by 57 (3 self)
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the orienteering problem. Our main result is a quasipolynomial time algorithm that yields an O(log OPT) approximation for this problem when f is a given submodular set function. We then extend it to the case when a node v is counted as visited only if the walk reaches v in its time window [R(v), D(v)]. We apply
Improved Algorithms for Orienteering and Related Problems
, 2007
"... In this paper we consider the orienteering problem in undirected and directed graphs and obtain improved approximation algorithms. The point to pointorienteeringproblem is the following: Given an edgeweighted graph G = (V, E) (directed or undirected), two nodes s, t ∈ V and a budget B, find an st ..."
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Cited by 53 (5 self)
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upon the 3approximation from [5]. • An O(log 2 OPT) approximation in directed graphs. Previously, only a quasipolynomial time algorithm achieved a polylogarithmic approximation [12] (a ratio of O(log OPT)). The above results are based on, or lead to, improved algorithms for several other related
OPT ICAL SPECTROSCOPIC STUDY OF
, 1985
"... mainly the natural phases selected from the 'garnierites ' of the supergene ore deposits of New Caledonia. Minerals which do not usually occur in New Caledonian parageneses were synthe sised, as they could represent intermediate phases of genetic importance. In the kerolitepimelite series ..."
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mainly the natural phases selected from the 'garnierites ' of the supergene ore deposits of New Caledonia. Minerals which do not usually occur in New Caledonian parageneses were synthe sised, as they could represent intermediate phases of genetic importance. In the kerolitepimelite series, a linear relationship occurred between the ratio I(13,20~/I(02,11) of the hk bands and Nicontent. Diffuse reflectance spectra were used to derive the crystal chemical parameters of Ni. These confirmed its divalent character and its occupation of octahedral sites; the resulting structural distortion was slight and could not be detected in some minerals. There was no optical evidence for Ni atoms in 4fold coordination. The two main parameters which showed significant variations among the studied phases were site distortion and crystal field stabilization energy (CFSE). Site distortion was at a maximum in trioctahedral smectites and sepiolite. CFSE depended on the mineralogy, crystallinity and chemical composition (Alcontent) of the phase. Finally, clay minerals are classified according to the increasing stability of Ni in the octahedral sheet, which has been tentatively related to the geochemical distribution of this element. Secondary minerals are usually enriched vs. primary ones and among them are nepouite and kerolite which exhibit a high CFSE in contrast to sepiolite.
Results 1  10
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