- From: Jim Hendler <hendler@cs.umd.edu>
- Date: Fri, 13 Jun 2003 06:53:50 -0400
- To: Jeremy Carroll <jjc@hpl.hp.com>, www-webont-wg@w3.org
At 11:34 AM +0300 6/13/03, Jeremy Carroll wrote:
>> 1200 seconds (which is admittedly quite a while).
>
>I would not be unhappy with longer ...
>
>With these sorts of problems care can often reduce 1200secs to <1sec, the
>problem is trying to reduce 1200 years to <1sec.
>
>Jeremy
Jeremy - you need to get over this bizarre affliction -- the time
these computations take is often not a feature of the system, but of
the PROBLEM.
Here's a simple example -- it is trivial to write a little program
to play tic-tac-toe in almost any system you give me that can
generate instances. On a 3x3 board, you need to store approximately
9!/2 (181,000) instances to enumerate the entire game tree using a
naive algorithm. On a 12x12 board this number goes to 144!/2 which
is somewhere on the order of 10^240 (give or take a few orders of
magnitude) - meaning there is no computer in the world that could
come even close to solving this problem in 1200 years.
By analogy to your arguments about OWL DL, no language of any type
that could encode tic-tac-toe could be decidable, since it could not
play 12x12 tic tac toe in any reasonable bounded time - is that
correct?
-JH
--
Professor James Hendler hendler@cs.umd.edu
Director, Semantic Web and Agent Technologies 301-405-2696
Maryland Information and Network Dynamics Lab. 301-405-6707 (Fax)
Univ of Maryland, College Park, MD 20742 *** 240-277-3388 (Cell)
http://www.cs.umd.edu/users/hendler *** NOTE CHANGED CELL NUMBER ***
Received on Friday, 13 June 2003 06:54:06 UTC