1. A method for process model validation, the method being performed by at least one processor, the method comprising: obtaining a process model, the model having (a) a directed graph with nodes that are associated with process steps, and with edges that are associated with a flow of execution from predecessor steps to successor steps, (b) pre-conditions and post-conditions associated with the process steps, such that a post-condition of a predecessor step of the predecessor steps can be a pre-condition for execution of a successor step of the predecessor step, and (c) variables to determine logical values of the pre-conditions and the post-conditions, the variables including a first variable, a second variable, and a third variable associated with the pre-condition of the successor step; performing process model validation on the obtained process model, the process model validation including detecting at least one process that is not executable, wherein the at least one process is non-executable if at least one process step is not executable, wherein the performing process model validation includes reducing a number of initial states associated with the process model, the number of initial states being dependent on a number of the variables, the pre-conditions, and the post-conditions, wherein the reducing the number of initial states includes: detecting dependencies between the variables that are required to determine the logical values of the pre-conditions including detecting the first variable to be dependent from the second variable if the first variable alone is not sufficient to determine a logical value of the pre-condition as false, and detecting the third variable to be independent from the first and second variables if the third variable alone is sufficient to determine the logical value of the pre-condition as false, and splitting the model into sub-models so that dependent variables remain within sub-models including a first sub-model and a second sub-model, the first sub-model including the first variable and the second variable, and the second sub-model including the third variable, wherein the performing process model validation includes checking the flow of execution with the pre-conditions and the post-conditions for possible combinations of the dependent variables for each sub-model separately including evaluating a sub-model of the sub-models to be valid if the checking of the flow of execution indicates that the steps of the sub-model can be executed and evaluating the model to be valid if the sub-models are evaluated to be valid.