1. In an electronic design automation (EDA) software tool in a computer, a method for proving equivalence between a first circuit design and a second circuit design, wherein the first circuit design includes a first division circuit and the second circuit design includes a second division circuit, the method comprising: the EDA software tool in the computer analyzing the first and second circuit designs to determine an input relationship between a set of inputs of the first division circuit and a set of inputs of the second division circuit, wherein the set of inputs of the first division circuit is different from the set of inputs of the second division circuit; the EDA software tool in the computer determining an output relationship between a set of outputs of the first division circuit and a set of outputs of the second division circuit based on the input relationship, wherein the input relationship is different from the output relationship; and the EDA software tool in the computer proving equivalence between the first and second circuit designs, wherein said proving involves using the output relationship as an assumption.