Dima Grigoriev Deviation Theorems for Solutions of Differential Equations and Applications to Lower Bounds on Parallel Complexity of Sigmoids. 23-33 1994 133 Theor. Comput. Sci. 1 db/journals/tcs/tcs133.html#Grigoriev94 http://dx.doi.org/10.1016/0304-3975(94)00061-1