A technique for adding range restrictions to generalized searching problems

In a generalized searching problem, a set $S$ of $n$ colored geometric objects has to be stored in a data structure, such that for any given query object $q$, the distinct colors of the objects of $S$ intersected by $q$ can be reported efficiently. In this paper, a general technique is presented for adding a range restriction to such a problem. The technique is applied to the problem of querying a set of colored points (resp.\ fat triangles) with a fat triangle (resp.\ point). For both problems, a data structure is obtained having size $O(n^{1+\epsilon})$ and query time $O((\log n)^2 + C)$. Here, $C$ denotes the number of colors reported by the query, and $\epsilon$ is an arbitrarily small positive constant

Finding k points with a smallest enclosing square

Let $S$ be a set of $n$ points in $d$-space, let $R$ be an axes-parallel hyper-rectangle and let $1 \leq k \leq n$ be an integer. An algorithm is given that decides if $R$ can be translated such that it contains at least $k$ points of $S$. After a presorting step, this algorithm runs in $O(n)$ time, with a constant factor that is doubly-exponential in~$d$. Two applications are given. First, a translate of $R$ containing the maximal number of points can be computed in $O(n \log n)$ time. Second, a $k$-point subset of $S$ with minimal $L_{\infty}$-diameter can be computed, also in $O(n \log n)$ time. Using known dynamization techniques, the latter result gives improved dynamic data structures for maintaining such a $k$-point subset

Evaluation of Digital Repositories from an End-users\u27 Perspective: The Case of the reUSE project

Along with the long-term preservation of digital publications the next important goal is public access and in this regard user-centred design of digital repositories. Several repositories worldwide have shown that users are their most critical element. Repositories as such are valuable only if used. The success of the repository is often influenced by the content and the design of the interface. The lack of content is the main reason for unsuccessful repository as well as design-centred interface. Many digital repositories' interfaces are design-centred rather than user-centred. Quite a few users claimed that the search interface was too complicated and distracting and that specific jargon, wording and explanation within the certain interface did not help them at all. This demonstration presents the results of end-user survey carried out in the reUSE project, in which we examined the usability of three different digital repositories from Austria, Estonia and Germany. The reUSE is a cooperative project from eContent scheme and involves national and university libraries and universities from Austria, Estonia, Germany and Slovenia. Evaluation of the digital repositories was one of the main goals. Overall aim of the evaluation was to make user-centred repositories which will be at the same time most efficient in technical and organizational regards

Enumerating the k closest pairs mechanically

Let $S$ be a set of $n$ points in $D$-dimensional space, where $D$ is a constant, and let $k$ be an integer between $1$ and $n \choose 2$. An algorithm is given that computes the $k$ closest pairs in the set $S$ in $O(n \log n + k)$ time, using $O(n+k)$ space. The algorithm fits in the algebraic decision tree model and is, therefore, optimal

Further results on generalized intersection searching problems: counting, reporting, and dynamization

In a generalized intersection searching problem, a set, $S$, of colored geometric objects is to be preprocessed so that given some query object, $q$, the distinct colors of the objects intersected by $q$ can be reported efficiently or the number of such colors can be counted efficiently. In the dynamic setting, colored objects can be inserted into or deleted from $S$. These problems generalize the well-studied standard intersection searching problems and are rich in applications. Unfortunately, the techniques known for the standard problems do not yield efficient solutions for the generalized problems. Moreover, previous work on generalized problems applies only to the static reporting problems. In this paper, a uniform framework is presented to solve efficiently the counting/reporting/dynamic versions of a variety of generalized intersection searching problems, including: 1-, 2-, and 3-dimensional range searching, quadrant searching, interval intersection searching, 1- and 2-dimensional point enclosure searching, and orthogonal segment intersection searching

An optimal algorithm for the on-line closest-pair problem

We give an algorithm that computes the closest pair in a set of $n$ points in $k$-dimensional space on-line, in $O(n \log n)$ ime. The algorithm only uses algebraic functions and, therefore, is optimal. The algorithm maintains a hierarchical subdivision of $k$-space into hyperrectangles, which is stored in a binary tree. Centroids are used to maintain a balanced decomposition of this tree