The key here is this..
> and the user has then responded with further information that says that
> n==m. The only reasonable conclusion given than information is that
> Maxima should return the same result as the earlier simplification.
Not only has the user failed, in orginally posing the problem, to
incorporate the relationship between n and m, but
1. Later imposes the condition that n=m !!!
2. This particular imposition means that Maxima will either divide by
zero, or has already done so.
This may become evident in using integrate, but it is hardly something
that can be "fixed" in integrate.
Systematically speaking, when dividing by n-m, the system can record the
assumption that n-m is not zero. And then later any attempt to make n-m=0
is refused. Consider the other places this matters, for sure: solve.
Simplification in general. Limits. Taylor series.
The conclusion above, that given the new information that n=m, the
calculation
should be restarted, is a stopgap approach. How far back do you go??
RJF