1. A computer-implemented method for real-time evaluation of a reverse query to an attribute-based access control (ABAC) policy (P), which is enforced to control access to one or more resources in a computer network, said method comprising the steps of: i) receiving a reverse query indicating a given decision (d), which is one of permit access and deny access, and a set (R) of admissible access requests, each of which comprises one or more attributes appearing in the ABAC policy and explicit values assigned to these; ii) extracting attributes to which all access requests in the set (R) assign identical values; iii) reducing the ABAC policy at least by substituting values for the extracted attributes; iv) caching the policy after said reducing as a simplified policy (P′); v) translating the cached simplified policy (P′) and the given decision (d) into a satisfiable logic proposition in Boolean variables (v i , i=1, 2,. .. ); vi) deriving all variable assignments (c j =[v 1 =x j1 , v 2 =x j2 ,. .. ], j=1, 2,. .. ) satisfying the logic proposition; and vii) extracting, based on the variable assignments thus derived, all access requests from the set (R) for which the ABAC policy (P) yields the given decision (d).