1. A method for modeling a change in a complex real system using comparison of at least two computer-based, data-processing models of the complex real system, the method comprising the following steps: by a computer, comparing a first model and a second model and determining predefined objects of the first model and the second model, wherein the predefined objects are associated with one another in the first model and the second model, wherein the first model and the second model of the complex real system are present and in each case model a system behavior by way of predefined objects that represent activities and units within the complex real system, wherein the first model is a separate and distinct representation of the complex real system when the complex real system is in a first condition, and wherein the second model is a separate and distinct representation of the complex real system when the complex real system is in a second condition; by a computer, determining the associations and differences in attributes of the predefined objects associated with one another in the first and the second model; and by a computer, using a comparison algorithm to automatically determine action steps required for conveying the complex real system from the first condition as represented by the first model into the second condition as represented by the second model; wherein the modeling of the change in the complex system, in the first model and the second model, on a lowermost description level applies a limited set of basic types representing the units within the complex real system and describing the units within the complex real system interaction; each basic type processes data, said data representing values of characteristics of the units mentioned; and the set of basic types comprises: a basic type “transfer”, which represents a transfer of units, leads through data for characterizing these units, and comprises one input as well as one output, a basic type “merge”, which represents a combining of units, links data for characterizing these units to one another, and comprises two inputs as well as one output, and a basic type “split”, which represents a division of units, determines data for characterizing units, which come from a dividing-up from data of a unit to be divided up, and comprises one input as well as two outputs, wherein in each type of the basic types, inputs serve for receiving data into respective basic types and outputs serve for transferring data out of respective basic types, and wherein computer-based, data-processing models of the complex real system are formed by way of forming a quantity of basic types and by way of linking inputs and outputs of these basic types; thereby modeling the complex system in the first condition and in the second condition to facilitate a computer analysis of the change in the complex system.