Computer Chess Club Archives


Search

Terms

Messages

Subject: Re: Never Say "Impossible"

Author: Jesper Antonsson

Date: 03:36:40 05/06/01

Go up one level in this thread


On May 05, 2001 at 23:10:20, Robert Hyatt wrote:
>On May 05, 2001 at 21:13:15, Jesper Antonsson wrote:
>>On May 04, 2001 at 22:05:51, Robert Hyatt wrote:

>>>Second, a tree search such as minimax is already known (and proven) to be NP.
>>
>>So, Tic-Tac-Toe (which can also be solved with minimax) is NP? Hardly.
>
>Yes it is, in fact.  If it has a tree shape, it is NP by definition.  NP
>doesn't mean specific instance problems are not solvable...

1. It is possible to write bad algorithms that solve polynomial problems in
   exponential time, with "tree shapes". That doesn't make them NP.

2. What is a larger instance of the "tic-tac-toe problem"? Before you claimed
   that the exponentiality existed as a function of search depth. Increase the
   search depth in the mini-max beyond nine in tic-tac-toe, and your search
   won't take longer time. *It has an upper time bound.* There is a similar
   limit in chess, it is just too large for us to ever attain.



This page took 0.05 seconds to execute

Last modified: Thu, 15 Apr 21 08:11:13 -0700

Current Computer Chess Club Forums at Talkchess. This site by Sean Mintz.