Performance ratio revisited: is PR > 90% realistic?

Problem Heuristic Performance Ratio New PR Run - time

The Steiner tree problem asks for the shortest tree connecting a given set of terminal points in a metric space. We design new approximation algorithms for the Steiner tree problems using a novel technique of choosing Steiner points in dependence on the possible deviation from the optimal solutions. We achieve the best up to now approximation ratios of 1.644 in arbitrary metric and 1.267 in rec...

Birthweight ratio revisited.

In order to test the hypothesis suggested in a recent report that the birthweight ratio might be a useful predictor of several important clinical outcome measures in babies of less than 31 weeks' gestation, we examined the association between the birthweight ratio and aspects of both short and long term outcome in 436 Leeds babies of less than 31 weeks' gestation. Unlike the report, and contrar...

Sensor Placement Revisited in a Realistic Environment

Ad-hoc networks of devices and sensors with (limited) sensing and wireless communication capabilities are becoming increasingly available for commercial and military applications. Under a national SensorNet initiative, we have built prototype deployment of a detection, identification, and tracking sensor-cyber network in a variety of locations including Washington D.C. and Port of Memphis. One ...

Semiparametric Likelihood Ratio Inference Revisited

2000 We extend the Semiparametric Likelihood Ratio Theorem of Murphy and Van del' Vaart for one-dimensional to Euclidean paramet(;rs of auy dimension. The as:VIrlptotic distribution of the likelihood ratio statistic for testing a k-dimensional Euclidean paramet'"r is shown to be the usual under the null hypothesis. This result is useful not only for testing purposes but also in forming likeliho...

Semiparametric Likelihood Ratio Inference Revisited