Kazunori Ueda Takayuki Ayano Taisuke Hori Hiroki Iwasawa Seiji Ogawa Hierarchical Graph Rewriting as a Unifying Tool for Analyzing and Understanding Nondeterministic Systems. 349-355 2009 ICTAC http://dx.doi.org/10.1007/978-3-642-03466-4_24 conf/ictac/2009 db/conf/ictac/ictac2009.html#UedaAHIO09