By Wolfgang Wasow (auth.)

My publication "Asymptotic Expansions for traditional Differential Equations" released in 1965 is out of print. within the virtually twenty years considering that then, the topic has grown quite a bit in breadth and intensive that an account of the current kingdom of data of all of the subject matters mentioned there couldn't be equipped into one quantity with no resorting to an overly terse type of writing. rather than project this sort of job, i've got focused, during this exposi­ tion, at the features of the asymptotic conception with which i've been rather involved in the course of these two decades, that's the character and constitution of turning issues. As in bankruptcy VIII of my prior publication, merely linear analytic differential equations are thought of, however the inclusion of vital new rules and effects, in addition to the improvement of the neces­ sary history fabric have made this an exposition of e-book size. The formal thought of linear analytic differential equations with out a parameter close to singularities with recognize to the self reliant variable has, lately, been vastly deepened by means of bringing to it equipment of contemporary algebra and topology. it's very possible that lots of those principles may be utilized to the issues pertaining to singularities with recognize to a parameter, and that i wish that this may be performed within the close to destiny. it really is much less most probably, despite the fact that, that the analytic, rather than the formal, facets of turning aspect concept will significantly take advantage of such an algebraization.