James Bailey Guozhu Dong Kotagiri Ramamohanarao On the decidability of the termination problem of active database systems. 389-437 2004 311 Theor. Comput. Sci. 1-3 http://dx.doi.org/10.1016/j.tcs.2003.09.003 db/journals/tcs/tcs311.html#BaileyDR04