Rook and Knight vs. Bishop Pair

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RobertJSacamano

This is my first post, and my question has probably been asked countless times, but here goes...

I know that a single bishop is considered slightly stronger than a single knight, and that the bishop pair is significantly stronger than two knights. I also know that even though rooks are said to be worth 5 points, and minor pieces only 3 points, the exchange is generally considered to be worth less than 2 points.

So what I'm wondering is this: How much stronger, if at all, is a rook and a knight than the bishop pair? I know the rook and knight should be stronger, but I feel like they're almost equal. I'd compare the difference between the two to the difference between 1 and 0.9.

Silfir

I think you have excellent company in the opinion that rook/knight and the bishop pair are of equal value - as far as I know Tarrasch frequently stated that belief.

I think the more pawns on the board and the more rigid their position (number of interlocked pawns), the better for the side with the knight. The rook is also great on an open board, but he doesn't need open diagonals, but open files, and just one, maybe two may be needed for the rook to penetrate, and rook and knight can actually combine their powers on a single square. If there are lots of interlocked pawns, chances are good one of the bishops will be "bad", as in highly hemmed in by its own pawns. On an open board, the bishops penetrate everywhere and exude greater control over the battlefield, though the rook is still a powerful foe, the knight may be too slow to be much of a help.

It's not a question to be answered definitely without a diagram. I think the rook and knight are, on average, somewhat superior, but the difference is hardly worth more than one pawn.

Nordlandia

For humans this might be around equal (practical play) , for computers it's not the case unfortunately. 

"The bishop pair and a pawn is worth a knight and a rook" 

I tried "Theme Blitz" on Fritz 13 with BB vs R & N and the outcome was not surprisingly victory for black all the time. Critter 1.6a white vs H3 Black - with all pawns intact.

Thereupon a slight improvment for the weaker side was made, mainly remove the central pawn on e7. This + first move made the starting evaluation to about ~ -0.55 for black.

Then i switched the engine placements and more draws was achieved. Of course 3 min is perhaps to low and can indirectly lead to minor errors. 

After two time control trails the general score is favourable for R & N.

Blitz 5m

 

Stockfish 11-05-13 64bit +102   ½½1½½1½   4.5/7

Houdini 3 Pro x64 -102  ½½0½½0½    2.5/7

Bishop Pair + Pawn vs Rook and Knight is to some degree weaker in engine play - this margin might disappear for humans. Unfortunately there is not many cases of this imbalance in games atleast from what i'm aware off.

 

Nordlandia

Garry Kasparov - Nigel Short, Kasparov vs Short (Rapid) 2015

[Fen - 2r3qk/1p4np/p6B/4Q2B/8/P7/1P4PP/6K1 w - - 0 1]

Analysis by Stockfish 030515 64 BMI2:

33.Bf3 Qf7 

+/=  (0.54 --)    Depth: 37/56   00:00:20  320MN, tb=2871

(05.05.2015)

 
Nordlandia
 

Intel i7-5960X Processor Extreme Edition (Overclocked to 4.1 GHz)
Komodo 8 GUI
6144mb hash each where possible
All engines 64-bit where available
Table memory 256mb (komodo)
5 piece tablebases (syzygy)
Both engines using 8 cores (hyper-threading disabled)
Ponder off
Default settings otherwice.
 
 
 
 
 
Nordlandia
Question here is if white can hold the position.


New game
5bk1/5ppb/7p/4N3/3R4/8/5PKP/8 b - - 0 1
 
Analysis by Stockfish 030515 64 BMI2:
 
41...f6 42.Nd7 Be7 43.f3 Kf7 44.Nb6 Bf8 45.Rd7+ Ke6 46.Rc7 Bf5 47.Nc4 h5 48.Kf2 g5 49.Rc6+ Ke7 50.Nd2 Kf7 51.Ne4 Be7 52.Ke3 g4 53.Nd6+ Kg6 54.Nc4 Kf7 55.fxg4 Bxg4 56.Rc7 Ke6 57.Kd4 Bf3 58.Ra7 Bd8 59.Ra3 Bg4 60.Ra6+ Kf7 61.Ne3 Be2 62.Ra2 Bb6+ 63.Ke4 Bb5 64.Rb2 
+/=  (0.65)    Depth: 38/56   00:01:37  2042MN, tb=634826
(,  07.05.2015)
 
 
 
Nordlandia
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Nordlandia
[COMMENT DELETED]
Nordlandia
Less than or equal to at most
As for rook and knight vs. two bishops and pawn, with nothing else but pawns on the board, the rook's side has a mild advantage, but add a rook to each side and the game is dead even. In general, with other pieces on the board, this imbalance should be considered even, with only a trivial edge for the rook's side.
When the side down the Exchange has the bishop pair, my data shows he needs only 1.15 pawns to make things even.
Many of the Classicists of the late nineteenth and early twentieth century claimed that two bishops versus rook and knight were equivalent.
In open positions where the knight has no outposts in the centre, the strength of two bishops and a pawn is no less (and tends to be greater) than that of a rook and knight.
 

NotNormLOL

lone two bishops vs a lone rook and knight is a draw