Abstract: A distributed computer system has computers storing data items each data item being assigned to one of a plurality of virtual directories. Each computer has at least one node of a virtual network (10) for directory look-up, with linking data comprising addresses of other nodes associated with the same virtual directory and software that, in response to an enquiry message either replies, identifying itself or forwards the message to another node of the network (10), according to whether the node is or is not associated with the directory specified in the enquiry message. Similarly, each computer has, for each item that it stores, a node of a virtual network for item look-up, with linking data comprising addresses of other such nodes associated with items assigned to the same virtual directory, so that these linking data together define a plurality of virtual networks for item look-up, each of which networks corresponds to a respective different virtual directory.

Abstract: A browsing process is driven by user interaction. The user is presented with a selection of items 511, 512, . . . etc from a range. The user can give inputs representing interest in one or other of the items displayed. The inputs represent rewards, which are distributed to attribute data items or “keywords” associated with the display items. These keywords are transparent to the user, but represent characteristics of the display items with which they are associated. The browsing system selects items for display according to a probabilistic function weighted to favour those having the keywords which have accrued the highest number of rewards, these being the display items having the most keywords in common with display items previously rewarded by the user during the browsing session. Partial or negative weightings may also be applied to the keyword associations, which are also taken into account in the selection process.

Abstract: Display location calculation means and methods for calculating a display location are disclosed. It has become common for users to indicate a point on a display in order to communicate with a machine. It is therefore necessary to be able to calculate the location on the display that is being indicated by the user. A display generator (123) is arranged in operation to generate a display in response to display data generated by a machine (111). A camera operable to generate image data representing at least part of the scene within the field of view of the camera (which part, includes at least a portion of the display) is carried in a pointer device (103). Computation means (111, 113, 115) are arranged in operation to receive the image data and the display data and to calculate from these data sets the position and/or orientation of the pointer device (103) relative to the display. A display location can then be calculated from the calculated position and/or orientation.