Abstract: A yo-yo has at least one sensor configured to measure a parameter related to movement of the yo-yo, a transmitter configured to transmit the measured parameter to the computing device. A server is configured to determine a trick performed with the yo-yo based on the measured parameter, and to communicate the determination to one or more computing devices of different players.

Abstract: This invention relates to a technique and system (34) for clustering a set of data points (18) in a data field. Clustering is performed by a set of rules which make no assumptions about the data fields. That is, the number of clusters, the distance between clusters, etc., need not be specified in advance. The invention calculates a distance R that is a function of the distances between each pair of points (18) in a data field. Operating on a chosen point, a parameter is calculated for each neighboring point within distance R from the chosen point. This parameter is proportional to the distance of the neighboring point to the chosen point. The chosen point P is then connected to a neighboring point on the basis of this parameter. All points, in any order are operating on as the new chosen point, so that the additional points may be linked to new chosen points in a similar manner. In this way, a tree-structure (22, 24) of connected points will form the desired clustering.