One of the problems of documenting software evolution appears with the extensive use of refactorings. This paper explores a method, based on graph transformation, to detect wether the evolution between two versions of a software system can be expressed by means of a sequence of refactoring operations. For this purpose we extend a graph representation format to use it for simple Java programs, and we show a sample implementation of the method using the AGG graph transformation tool. In case a refactoring sequence exists, our technique can help reveal the functional equivalence between the two versions of the system, at least, as far as refactorings can assure behaviour preservation. Presented in 2007 at the Third International ERCIM Symposium on Software Evolution (http://ercim-news.ercim.eu/en72/joint-ercim-actions/third-international-ercim-symposium-on-software-evolution).