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Motion P1788.1/M001.02 -- YES



I vote YES to the text of Clause 4 of Nov 30, 2015.

As for "Natural Interval Extension" -- it seems to me that this is the
proper term.  Is is also consistent with the parent standard 1788-2015.

Now, there may indeed be confusion if others have used this term to
denote what I might call "Moore Interval Extension".

So I would suggest, as an editorial comment, that we add the following
at the end of Clause 4.4.4:

   The term "Natural Interval Extension" has frequently been used to
   denote the result of expression evaluation, as opposed to the hull
   of the range.  The term "Moore Interval Extension" might have been
   more appropriate for this.

Michel.

P.S.  The Wikipedia article does not define the "function rule" that
      it applies to its definition of "natural interval extension".
      The problem of course is that many expressions can be used to
      compute a function, and some functions might not even use an
      expression -- they might use table-based interpolation for example.
      So while there may be a "natural interval expression extension",
      the notion does not make sense for a *function*.

      An article by Alexandre Goldsztein uses "Natural A-E extension"
      which however restrics the expression to single-use variables.
---Sent: 2015-12-07 21:33:52 UTC