Abstract: Methods and devices for controlling access to sensitive data stored in a computer system are provided. For at least some data entries in a dataset, each identified by a respective key, an indicator of which zero or more conditions of a plurality of queries are satisfied by that data entry is generated. The keys are grouped into cohorts based on the indicators, at least some of the cohorts comprising keys identifying data entries satisfying the same zero of more conditions. A first output is transmitted to the first computing device comprising an identifier of a first cohort and an indication of a condition which is satisfied by data entries identified by keys in the first cohort. A second output is transmitted to a second computing device comprising an identifier of the first cohort and a set of keys corresponding to the data entries in the first cohort.

Abstract: A method, system and program product for operating a data processing system comprises displaying on a display device a plurality of nodes of a network and a grid of intersection points, each intersection point either indicating the existence of a connection between two nodes, or indicating the lack of a connection between two nodes. Following receipt of a first user input at a user interface device, the first user input comprising selection of an intersection point, and a second user input at a user interface device, the second user input indicating a change for the selected intersection point, the change comprising an addition, deletion or amendment of a connection corresponding to the selected intersection, the display of the grid of intersection points is updated.