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Subject: Re: Promotion frequency

Author: Shane Hudson

Date: 14:48:09 07/23/02

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On July 23, 2002 at 03:11:17, Dann Corbit wrote:

>On July 23, 2002 at 03:04:39, Pham Hong Nguyen wrote:
>
>>Hey Dann, I did not say about your test set - yes, all games of that test set
>>were artificially created to illustrate how important underpromotions are.
>>However, I am mentioning about _real_ games - other story.
>
>Almost all of those positions I posted are from *REAL GAMES*.  Only a very tiny
>fraction are made up positions.
>
>>If you or someone could (or I will do when I have spare time), do a small
>>research about underpromotions in real games (of any database): count and report
>>total number of underpromotions / total number of promotions. The statistics
>>will help us on decision of design.
>
>The amount of useful underpromotions in real games will definitely be higher
>than you think.  If it is as small as one in a million games where
>underpromotion provides benefit, I will be utterly astonished.

I investigated this once for the purpose of improving material and
position search times in my database app Scid.

Here are stats on the number of games containing a promotion to each
type of piece in a database of 594,803 mostly master-level games:

Piece    Games    Freq per 1000 games
-------------------------------------
Any      24747         41.61
 Q       24083         40.50
 N         506          0.85
 R         227          0.38
 B          72          0.12
-------------------------------------

Whether many of those promotions to Rook or Bishop were actually
useful (superior to a Queen promotion) is anyone's guess. I suspect
most occurred in situations where the piece will immediately get
taken anyway.

Cheers,
Shane



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