In this paper, we introduce and study two new search models on digraphs: the directed searching and mixed directed searching. In these two search models, both searchers and intruders must follow the edge directions when they move along edges. We prove the monotonicity of both search models, and we show that both directed and mixed directed search problems are NP-complete.

Recent work on searching the Semantic Web has yielded a wide range of approaches with respect to the style of input, the underlying search mechanisms and the manner in which results are presented. Each approach has an impact upon the quality of the information retrieved and the user’s experience of the search process. This highlights the need for formalised and consistent evaluation to benchmar...

Real-time heuristic search algorithms that precompute search space specific databases have demonstrated exceptional performance in video-game pathfinding. We discuss the first steps towards extending these algorithms to additional search spaces which benefit from the real-time property. We present our initial progress in characterizing the performance of current algorithms based on search space...

We discuss an implementation of a derivative-free generating set search method for linearly constrained minimization with no assumption of nondegeneracy placed on the constraints. The convergence guarantees for generating set search methods require that the set of search directions possesses certain geometrical properties that allow it to approximate the feasible region near the current iterate...

In this article a primal-dual interior-point method for solving linear programs is proposed. A new approach for generating higher-order search directions, and a new method for an eecient higher-order subspace search along several search directions are the basis of the proposed extension. The subspace search is reduced to a linear program in several variables. The method using the simplest (two-...

It has been shown recently that the efficiency of direct search methods that use opportunistic polling in positive spanning directions can be improved significantly by reordering the poll directions according to descent indicators built from simplex gradients. The purpose of this paper is twofold. First, we analyze the properties of simplex gradients of nonsmooth functions in the context of dir...

This paper surveys the research field of semantic search, i.e. search utilizing semantic techniques or search of formally annotated semantic content. The survey identifies and discusses various prevalent research directions in semantic search, as well as extracts common methodology used in them.

User and behavioral modeling plays a critical role in a variety of online services such as web search, advertising, ecommerce, and news recommendation. For example, our ability to accurately interpret the intent of a web search can be informed by knowledge of the web pages a searcher was viewing when initiating the search or recent actions of the searcher such as queries issued, results clicked...

In this paper, we report results of an investigation where thirty subjects were observed performing subject-based search in an online catalog system. The observations have revealed a range of misconceptions users have when performing subject-based search. We have developed a taxonomy that characterizes these misconceptions and hypotheses about the causes of the misconceptions. Directions for im...