(05/13/2009, 04:52 PM)tommy1729 Wrote: are there meromorphic functions f(x) so that they commute with exp(x) ?

I'm not sure if this is important, but I think what is important is whether or not:

"For all f(x) that satisfy , there exists a unique real number t such that ."

I'm not convinced that this is always true for holomorphic/meromorphic functions. I'm sure its false for for arbitrary (or piecewise-defined) functions. I also think this would be useful in characterizing fractional iterates.

Andrew Robbins