Jan Paredaens Peter Peelman Letizia Tanca Merging Graph-Based and Rule-Based Computation: The Language G-Log. 267-300 1998 25 Data Knowl. Eng. 3 db/journals/dke/dke25.html#ParedaensPT98 http://dx.doi.org/10.1016/S0169-023X(97)00020-7