We propose a new stochastic search algorithm for Gaussian graphical models called the mode oriented stochastic search. Our algorithm relies on the existence of a method to accurately and efficiently approximate the marginal likelihood associated with a graphical model when it cannot be computed in closed form. To this end, we develop a new Laplace approximation method to the normalizing constan...

This paper derives upper bounds on the expected number of search tree nodes visited during an m-solution backtracking search, a search which terminates after some pre-selected number m problem solutions are found. The search behavior is assumed to have a general probabilistic structure. Our results are stated in terms of node expansion and contraction. A visited search tree node is said to be e...

This paper deals with model order reduction for linear stable discrete-time systems while minimizing the l∞gain of the error system. Our approach considers explicitly time domain performance and not frequency domain performance like most other approaches do. A convex programming problem expressed in terms of linear matrix inequalities combined with a line search algorithm is formulated to provi...

Parallel heuristic search algorithms are widely used in artificial intelligence. This paper describes novel parallel variants of two standard sequential search algorithms, the standard Davis Putnam algorithm (DP); and the same algorithm extended with conflict-directed backjumping (CBJ). Encouraging preliminary results for the GpH parallel dialect of the non-strict functional programming languag...

We present a simple algorithm for the maximum spanning star forest problem. We take advantage of the fact that the problem is a special case of complementary set cover and we adapt an algorithm of Duh and Fürer in order to solve it. We prove that this algorithm computes 193/240 ≈ 0.804-approximate spanning star forests; this result improves a previous lower bound of 0.71 by Chen et al. Although...

Nowadays an increasing amount of data stored in the public cloud need to be searched remotely for fast accessing. For the sake of privacy, the remote files are usually encrypted, which makes them difficult to be searched by remote servers. It is also harder to efficiently share encrypted data in the cloud than those in plaintext. In this paper, we develop a searchable encryption framework calle...

This A non-linear model of query modifications during a single session of user searching on the Web is evaluated. In addition to a sequential query modification, in which any query may be reformulation of its direct predecessor, the model allows non-linear interpretation of query reformulations: branching, merging, re-merging (merging of earlier branched chains) and non-sequential execution of ...

Before the search it is impossible to predict how many looks will be necessary to locate the target. A policy is a plan of search that tells where the nth look will be made--should it be necessary. For any policy, if P ( k ) is the probabil i ty tha t the target is found on or before the kth look, C(]c) is the total cost of the first k looks, and C is the random total cost, then the expectation...

Petroleum Allocation is an important link for the integration of Petroleum Supply Chain at PETROBRAS as it is responsible for refining the strategic supply planning information to be used at the operation levels. In this work we describe how mathematical programming is being used to solve the Petroleum Allocation Problem and we show the effectiveness of a local search method by optimization to ...