quuen sac for two rooks

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newenglandsun
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Joined: Sat Nov 28, 2015 4:24 am

quuen sac for two rooks

Post by newenglandsun » Fri Dec 04, 2015 10:31 pm

[pgn][Event "Game time control: 3m + 4s"]
[Site "shredderchess.net"]
[Date "2015.12.04"]
[Round ""]
[White "virac2015"]
[Black "newengland7"]
[WhiteElo "1239"]
[BlackElo "1329"]
[Result "0-1"]

1.Nc3 f5 2.b3 e5 3.Bb2 Nf6 4.d3 d6 5.e4 g6 6.f3 Bg7 7.Qd2 fxe4
8.dxe4 O-O 9.O-O-O Nc6 10.Bc4+ Kh8 11.Nge2 h5 12.h4 Kh7 13.Kb1
Bh6 14.f4 exf4 15.Nxf4 Ng4 16.g3 g5 17.Nxh5 gxh4 18.Qe2 Nf2 19.Rxh4
Qxh4 20.gxh4 Bg4 21.Qe1 Nxd1 22.Nxd1 Bxh5 23.e5 Nxe5 24.Qe4+
Bg6 25.Qxb7 Nxc4 26.Qxc7+ Bf7 27.bxc4 Rab8 28.Qxd6 Bg7 29.Qd3+
Bg6 30.Qe2 Rxb2+ 31.Nxb2 Rb8 32.Kc1 Bxb2+ 33.Kd1 Rd8+ 0-1[/pgn]

Dann Corbit
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Re: quuen sac for two rooks

Post by Dann Corbit » Fri Dec 04, 2015 11:40 pm

It's generally not considered a sacrifice to give up a queen for 2 rooks, because 2 rooks are better than a queen.

Dann Corbit
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Re: quuen sac for two rooks

Post by Dann Corbit » Sat Dec 05, 2015 2:05 am


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Nordlandia
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Re: quuen sac for two rooks

Post by Nordlandia » Sat Dec 05, 2015 2:27 am

Dann Corbit wrote:It's generally not considered a sacrifice to give up a queen for 2 rooks, because 2 rooks are better than a queen.
«A natural assumption is that the two rooks will be stronger than the queen in the majority of positions; another is that a material balance is struck when the side with the queen has an extra pawn. I must admit that, when I examined top-flight games from my database, I was surprised to see that the queen outscored the rocks. I would have predicted a small edge for the rocks but in fact the side with the queen managed 55%»

From a statistical viewpoint, 55% is equivalent to home field advantage in soccer or advantage of playing white.

«The Queen is weaker than two Rooks if the hostile King is protected against Checks, otherwise it may be stronger. Ceteris paribus, it would appear that the Queen is trifle weaker than two Rooks»

Definition of trifle "something that does not have much value or importance"
"With other things the same" or "other things being equal or held constant"

Dann Corbit
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Re: quuen sac for two rooks

Post by Dann Corbit » Sat Dec 05, 2015 2:35 am

These are the values used by stockfish (researched with hundreds of thousands of games played):

RookValueMg = 1270, RookValueEg = 1281,
QueenValueMg = 2521, QueenValueEg = 2558,

since 1270*2-2521=19
and 1281*2-2558=4

it appears that they are close enough in value (just counting the wood and ignoring that a pair can support one another -- there are, of course, many other interactions that may weight the value one way or another) to be a toss-up.

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Nordlandia
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Re: quuen sac for two rooks

Post by Nordlandia » Sat Dec 05, 2015 3:23 am

Dann Corbit wrote:These are the values used by stockfish (researched with hundreds of thousands of games played):

RookValueMg = 1270, RookValueEg = 1281,
QueenValueMg = 2521, QueenValueEg = 2558,

since 1270*2-2521=19
and 1281*2-2558=4

it appears that they are close enough in value (just counting the wood and ignoring that a pair can support one another -- there are, of course, many other interactions that may weight the value one way or another) to be a toss-up.
You're right 1281 (x2) = 2562/2558 =1,00156 which is statistically meaningless.

Do you know the value Stockfish used in case "The exchange" and bishop pair.

Dann Corbit
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Re: quuen sac for two rooks

Post by Dann Corbit » Sat Dec 05, 2015 4:49 am

Nordlandia wrote:
Dann Corbit wrote:These are the values used by stockfish (researched with hundreds of thousands of games played):

RookValueMg = 1270, RookValueEg = 1281,
QueenValueMg = 2521, QueenValueEg = 2558,

since 1270*2-2521=19
and 1281*2-2558=4

it appears that they are close enough in value (just counting the wood and ignoring that a pair can support one another -- there are, of course, many other interactions that may weight the value one way or another) to be a toss-up.
You're right 1281 (x2) = 2562/2558 =1,00156 which is statistically meaningless.

Do you know the value Stockfish used in case "The exchange" and bishop pair.
Don't know. In actual runtime behavior, there are many different factors that create the evaluation.

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