"Seabook" wrote in message
om...
Hi guys,
Do any of you guys know actual chess games or problems where queening
a pawn to a queen instead to just a rook or a bishop gives results
worse than queening to rook or bishop?

The reason I'm asking for these is I was having a discussion about
"optimizing" a computer chess engine with an expert in the field
(Guess who that is.). I first suggested that the chess engine could
just skip over the analysis of lines where a pawn is queened to a
bishop or a rook since queening to a queen should give the same, if
not better results. Lines where the pawn is queening to a knight
should not be skipped over, of course, because its movement is not
encapsulated in that of a queen. But a few hours after I got a
response from the expert, an abstract exception popped up in my head.
That is, queening to a queen could actually be worse than queening to
just bishop or rook.

Now I need actually example game setups that can confirm my fears.

You can search a large PGN files for "=R" or "8R" (or "=N", or "8N", etc.)
patterns. For example:

[Event "?"]
[Site "Vienna gt"]
[Date "1904.??.??"]
[Round "?"]
[White "Schlechter C"]
[Black "Wolf H"]
[Result "1-0"]
[ECO "C30/03"]

1.e4 e5 2.f4 Bc5 3.Qf3 d6 4.fxe5 dxe5
5.Qg3 Qf6 6.Nf3 Nd7 7.Bc4 Qg6 8.Qxg6 hxg6
9.Nc3 c6 10.Ng5 Nh6 11.d3 Nb6 12.Bb3 Ke7
13.Nf3 Nd7 14.Nd1 f6 15.Be3 Bxe3 16.Nxe3 Nc5
17.Nh4 Nxb3 18.Nxg6+ Kd8 19.axb3 Re8 20.O-O Be6
21.h3 Bf7 22.Nh4 Ke7 23.Nhf5+ Nxf5 24.Nxf5+ Kf8
25.h4 Be6 26.g4 Bxf5 27.Rxf5 Ke7 28.Kg2 Rh8
29.Kg3 a5 30.g5 b6 31.Kg4 Ke6 32.Raf1 Rag8
33.h5 Ke7 34.R1f2 Kd7 35.R5f3 Ke7 36.Rf1 Kd7
37.Kh4 Ke6 38.gxf6 g6 39.f7+ Rxh5+ 40.Kg4 Rf8
41.Rf6+ Kd7 42.R1f2 Rh1 43.Kg5 Rfh8 44.f8N+ 1-0