nczempin wrote:Knight promotions are even rarer, after all I started this thread because it so rarely happens in a real game (I'm not sure I agree with hgm's 1 %, actually I would think intuitively that it comes up not one, but two orders of magnitude less frequently---but I haven't looked through all Eden's games to check).
I just found this on Wikipedia's underpromotion article.
In the 2006 ChessBase database of 3,200,000 games, the breakdown of games in which promotions occur (counting games in which multiple promotions of the same type by the same player occur only once) is approximately:
* queen - 96.9%
* knight - 1.8%
* rook - 1.1%
* bishop - 0.2%
This suggests approximately 3% of all promotions are underpromotions. The frequency of truly significant underpromotions is, however, less than this.
Since these are statistics just for games where promotion occurs, I looked up Promotion in Wikipedia and found this:
In the 2006 ChessBase database of 3,200,000 games (largely grandmaster- and master-level), about 1.5% of the games contain a promotion.
So the percentage of all games in the database that would contain underpromotion would be approximately 0.046%.
So HGM's 1% does indeed sound quite high compared to these statistics if he's referring to total games played, which is how his comment reads. But perhaps he really meant 1% of promotions rather than 1% of games. At any rate, it seems your intuition here was pretty accurate in this case. But I'm still left wondering how many of those 3.1% of promotions really need to be underpromotions, and how many are just people underpromoting because they can. But if I had to guess I guess I'd say that a fair amount of the knight promotions are legitimate, but that most of the rook promotions are not.
