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Subject: Re: O(1) garbage

Author: Jeremiah Penery

Date: 17:53:49 05/15/01

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On May 15, 2001 at 18:11:57, Jesper Antonsson wrote:

>On May 15, 2001 at 11:53:32, David Rasmussen wrote:
>
>>On May 15, 2001 at 06:40:58, Martin Schubert wrote:
>>
>>>
>>>O-Notation is never about one specific problem, it's about one "family" of
>>>problems. If you want to look at the asymptotical behaviour of chess, you need
>>>an input n, for example the size of the board. Other things don't make sense.
>>>You can't say, something is O(1) because of something is bounded. First you have
>>>to define what your "n" is, and then look at the asymptotical behaviour.
>>>It doesn't matter for example, if you play chess only on a 8x8-board. The
>>>question is "what would happen if you played on a nxn-board?".
>>>
>>>Martin
>>
>>Exactly.
>
>Most of us are talking about chess and "n" as "target search depth".

With the current tree-searching algorithms, do you not agree that depth N+1
takes exponentially longer than depth N?  (Ignore the fact that N has a maximum
bound - that is completely irrelevant, and has nothing to do with complexity
analysis.)

I grant that _maybe_ it's possible for an algorithm to be constructed that
reduces chess to something less than O(exp(n)), but still not O(1).

O(1) implies that the algorithm is solved in _constant_ time, REGARDLESS OF N.
If you're using ply depth as N, I really don't see how you can conclude O(1).
It's clearly seen that for all reachable N (reachable within the potential life
of the universe, perhaps), the behavior is O(exp(n)).



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