We propose a new visualization of family relations, called family metro map, which is inspired by the famous London Underground Map. A family is represented by a metro line, where the parents are the end nodes and the children the intermediate nodes. We introduce family trees as rooted binary trees and consider the problem of automatically drawing a family metro map for a given family tree without crossing line segments, where the successive nodes of a metro line are placed at equal distances. The inter-node distance may be chosen to depend on the generation of the family, such that metro lines of earlier generations are shown more prominently than metro lines of later generations.

Despite, or exactly because of the wealth of video content available on the Web, it is often cumbersome to obtain access to exactly the content you like. It is an active process of filtering and making choices, often requiring searches through long lists of alternatives.

We consider the problem of determining the minimum number Nd of unit disks that is required to block all rays emanating from a point P in the two-dimensional space, where each disk has at least a distance d to point P and to any other disk. We study the asymptotic behavior of Nd, as d tends to infinity. By deriving upper bounds and lower bounds, we prove that pi2/16 ≤ lim_{d -> infinity} N_d/d2 ≤ 18/pi2, where the upper bound is based on establishing an interesting link between unit disks positioned on a regular triangular grid and Farey sequences from number theory. By positioning point P as well as the centers of the disks on the grid points of such a triangular grid, we create hexagonal rings of disks around P. We prove that we need exactly d-1 of these hexagons to block all rays emanating from P.

Recommender systems are increasingly being employed to personalize services, such as on the web, but also in electronics devices, such as personal video recorders. These recommenders learn a user profile, based on rating feedback from the user on, e.g., books, songs, or TV programs, and use machine learning techniques to infer the ratings of new items.

Saha, Mukherjee, and Tripathi (see ibid., vol.6, no.6, p.779-796, 1998) present and analyze an ATM cell scheduling algorithm called carry-over round robin. Unfortunately, one of the basic lemmas in their paper, related to the performance of this algorithm, does not hold. This adversely affects the delay and fairness properties that they subsequently derive. To substantiate this, we describe carry-over round robin and present a counterexample to the lemma. We end with some concluding remarks.