© 2001 by London Mathematical Society
A Local Limit Theorem for Moderate Deviations
Department of Mathematics, University of Manchester Oxford Road, Manchester M13 9PL; e-mail: rad{at}ma.man.ac.uk
Received 24 May 1999. Revision received 2 December 1999. Revision received 1 February 2000.
The purpose of this note is to establish a uniform estimate for the mass function P(Sm = y) of an integer-valued random walk when y
and
where µ isthe mean of the step distribution. (The local central limit theorem provides such an estimate when (
is bounded.) The assumptions are that the mass function p of the step distribution is regularly varying at
with index
, where
> 3, and that
for some
' > 2. From this result, a ratio limit theorem is derived, and this in turn is applied to yield some new information about the spacetime Martin boundary of certain random walks.