Using time dependent variables for hazard analysis

The present paper considers the problem of hazard in combinatorial logic structures . We start from time constants method but we shall prove that this is not error free (there are situations when this method fails to point hazards in a combinatorial logic circuit). So we shall define an improvement for this method, improvement that will consider, among other features, the specific function implemented by the gates used (we are mostly interested by the inverting characteristic). In this endeavor we shall define a new type of operator and a new type of variable, both of them applicable when propagating the switching times for a specific circuit. The mentioned method is a very laborious one (considers all the possibilities disregarding the specific function implemented by a circuit). We shall prove that only a strictly limited number of situations should be considered in conjunction with the function that is being implemented by the circuit analyzed. In order to achieve this goal we shall express the logic function with respect to a new logic variable that is dependent by time. Operations with this new variable prove to have some very interesting properties (that we prove in the paper) that will allow us to restrain the window of possibilities of hazardous functioning to a very narrow one.