I really don't understand rules and patterns



I think that defrule, tellsimp, etc used to have warnings about certain 
kinds of rules.
They seem to have been removed.  I think because people did not 
understand them and
ignored them.  So someone decided to remove the warnings instead of 
trying to explain
them, or do something useful to deal with what is, at best, a 
complicated situation
in any computer algebra system trying to do some mixture of syntactic 
and semantic
matching.

My PhD thesis describes the matching, at least as originally written.

RJF