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Multiple values for R4RS.

   Date: Tue, 22 Aug 89 22:15:25 -0500
   From: R. Kent Dybvig <dyb@iuvax.cs.indiana.edu>

   If we decide to add "accepts?" to the language, we would have to say
   that an implementation is free to return #t if it cannot determine
   whether or not a given number of arguments is accepted by a given
   procedure.  An implementation might even define "accepts?" as:

      (lambda (procedure arity) #t)

   This may seem to water down the predicate, but it only makes explicit
   that which must already be true.

Please explain in what cases you believe ACCEPTS? is inherently undecidable.
The above message implies there are such cases, but they are not obvious to me.

Morry Katz