A process is described for catalytic cracking of hydrocarbon feedstocks from petroleum refining which increases substantially the yields of light olefins. For example, a data processing system is disclosed that includes: a data detector circuit, a filter circuit, a gain error generation circuit, and a multiplier circuit. The covering is computed by finding optimal or near-optimal coverings for privileged users for CC elements that are proper subsets of U. Furthermore, a trusted relationship defined by a system administrator of the centralized server may be applied to a first one and a second one of the set of organizations.