Bruno Courcelle Christian Delhommé The modular decomposition of countable graphs. Definition and construction in monadic second-order logic. 1-38 2008 394 Theor. Comput. Sci. 1-2 http://dx.doi.org/10.1016/j.tcs.2007.10.046 db/journals/tcs/tcs394.html#CourcelleD08