Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!asuvax!noao!arizona!dave
From: dave@cs.arizona.edu (Dave P. Schaumann)
Newsgroups: comp.software-eng
Subject: Re: Tolerance  (was Re: Reusability considered harmful??(!!))
Message-ID: <785@caslon.cs.arizona.edu>
Date: 4 Feb 91 23:45:42 GMT
References: <1401@ucl-cs.uucp> <27A9B451.48BF@tct.uucp> <15863.27ad36b6@levels.sait.edu.au> <777@caslon.cs.arizona.edu> <KHB.91Feb4103837@chiba.Eng.Sun.COM>
Organization: U of Arizona CS Dept, Tucson
Lines: 39

In article <777@caslon.cs.arizona.edu> I wrote:
>   Numerical analysis aside, I can't imagine a single instance of
>   "close is good enough".

khb@chiba.Eng.Sun.COM (Keith Bierman fpgroup) wrote:
>Most code optimizations, to wit:
>	register allocation (must be correct, but need not be optimal)
>	instruction scheduling (ditto)
>	etc.
>and
>	traveling salesfolk (ditto)
>	chess/games in general  programs (ditto)
>	etc.

cwk@ORCRIST.GANDALF.CS.CMU.EDU (Charles Krueger) wrote:
>How about weather predictions?  [Mentions other simulations]
>
>What goes on inside the computer, however, is still as precise as ever.

djbailey@skyler.mavd.honeywell.com wrote
>[...]
>"Tolerance" is appropriate to higher level system requirements.  If 
>you could quantify the tolerance in requirements, you could have a 
>very significant impact on how software development contracts are 
>written and probably reduce a lot of arguments.

Ok, so I stand corrected.  There are a lot of applications out there that
don't need exact answers.  But my question was in the context of code re-use.
How could you say something like, "well, I really need a stack, but I'll
settle for something sort of stacky"?  Will we see code like this in the
future:

  assert( stackyness(re_used_type) > 0.9 ) ; /* stackyness(a real stack)=1.0 */

I can't see how the "tolerence paradigm" could possibly lead to a reasonable
means of code re-use.

Dave Schaumann		|  And then -- what then?  Then, future...
dave@cs.arizona.edu	|  		-Weather Report