FREDERICK A. HOWES
We conclude this introduction by establishing some notational conventions. Order
relations such as 0(e), o(l) are meant to hold uniformly in all the other variables, as
e - 0 . Partial derivatives will be indicated by subscripts, e.g.,
fy = 3f/3y , fyTyf = 32f/3y'9y' .
Finally, we assume throughout that the small parameter e is positive.