Albert Atserias Andrei A. Bulatov Anuj Dawar Affine systems of equations and counting infinitary logic. 1666-1683 2009 410 Theor. Comput. Sci. 18 http://dx.doi.org/10.1016/j.tcs.2008.12.049 db/journals/tcs/tcs410.html#AtseriasBD09