07-203
To: J3
From: Malcolm Cohen
Subject: Models
Date: 2007 May 01

1. Introduction

[339:13.3p6] uses "determine" wrongly, and is redundant.  It also uses
"available" incorrectly (it is not, in fact, always available).

The "extended model" of real numbers would be more usefully defined in
only one place (13.4) and we can then call it the extended model and
not repeat the definition.

2. Discussion

13.3 is "Bit model".  13.4 "Numeric models" contains similar (but correctly
worded) witter about the inquiry functions.  Also, it sounds a bit weird to
talk about a "manipulation function" providing some [value] related to the
model.  There does not seem to be any particularly good reason for keeping
this text in either case; but if we do, it should be correctly and
consistently worded.

(Also, although EXPONENT is characterised as a manipulation function, it
does not seem more manipulative than LBOUND which is characterised as an
inquiry function.  Maybe this would bear further examination.)

Finally, many of the uses of the extended model are currently
contradictory, in that the Description (at least) constrains the
result or the argument to be an ordinary model number.

3. Edits to 07-007r1 re "inquiry" functions.

ALTERNATIVE 1: Delete redundancies.

[339:13.3p6] Delete.
[339:13.4p7+6-8] Delete the last sentence "The floating-point... models.".

ALTERNATIVE 2: Fix offending wording.

[339:13.3p6]
   "is available to determine"
-> "provides the value of the".

4. Edits to 07-007r1 re "extended model"

[339:13.4p7+] Add new paragraph
  "There is also an extended model set for each kind of real <x>; this
   extended model is the same as the ordinary model except that there are
   no limits on the range of the exponent <e>."
and index "extended real model" and "model!extended real".

[375:13.7.66p1] "model" -> "extended model"
{Fix contradiction.}

[375:13.7p5+1]
  Change "model" -> "extended real model",
  Change "that has the radix of X but no limits on exponent values"
  to     "for the kind of X".
{Reference extended model, don't define it.}

[378:13.7.71p1] "model" -> "extended model"
{Fix contradiction.}

[378:13.7.71p5+1]
  Change "model" -> "extended real model",
  Change "that has the radix of X but no limits on exponent values"
  to     "for the kind of X".
{Reference extended model, don't define it.}

[417:13.7.156p1] "Model number" -> "Number", "model" -> "extended model".
{This edit is the same as in my paper on UTI 093.}

[418:13.7.156p5+1]
  Change "model that has the radix of X but no limits on exponent values"
  to     "extended real model for the kind of X".
{Reference extended model, don't define it.}

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