1. An automated computer-assisted method for assigning work tasks to users in a workflow management system, comprising the steps of: providing with a computing device at least one first directed graph and at least one second directed graph that respectively comprise objects and connections between these objects, wherein objects, the connections of which originate directly or indirectly from a parent object, form sub-objects of the parent object; providing with the computing device at least two different authorization categories, wherein a first authorization category represents a local authorization that is limited to a respective object and a second authorization category represents an authorization that applies to the respective object and at least part of any sub-objects of the respective object, and wherein utilizing the at least two different authorization categories in conjunction with the at least one first directed graph and the at least one second directed graph results in a reduced allocation of computer memory needed for storing a plurality of authorizations with respect to a user; receiving an assignment at the computer device from a provided user interface, with respect to a user, of at least one of the first and second authorization categories to at least one object in the first graph and to at least one object in the second graph in order to respectively obtain assigned objects in the first and the second graphs; automatically forming a Cartesian product of the first and the second graph with the computing device in order to obtain a product graph; automatically identifying, with the computing device, a product object of the product graph resulting from the assigned object of the first graph and the assigned object of the second graph and identifying, with the computing device, sub-objects of the product object, to which the second authorization category also applies, if applicable; automatically assigning, with the computing device, the user to the identified product object and the identified sub-objects of the product graph; obtaining from a provided user interface, with the computing device, a responsibility request with respect to a requested object of the product graph; automatically determining, with the computing device, that the requested object is assigned to the user; and automatically assigning, with the computing device, the request to the user in response to determining that the requested object is assigned to the user.