Ceteris paribus

• «When the side down the exchange has the bishop pair, my data shows he needs only 1.15 pawns to make things even»  - Larry Kaufman
• «Adding the better cooperation of the rook with the bishops, many soviet theoreticians believed that, in active positions rook and two bishops outperform two rooks and a knight»
• «Many of the classicists of the late nineteenth and early twentieth century claimed that two bishops versus rook and knight were equivalent. i don’t believe that this is the case, i.e., i think the extra material will usually win out, but this view continues to influence chess thinking to some extent even today» - Steve Mayer 1997
• «A pair of bishops shouldn't be underestimated, but the rook and knight are still superior» - Glenn Flear 2007

In-depth analyse - http://nb.lichess.org/tAJLX5VQ#62

• 8 Cores
• 2048mb hash
• 5-men tablebases

The defender probably has more chances of successfully defending with the pair of bish-
ops than "with other minor piece combinations. This seems to hold true even when the board
isn’t opened up for bishops. Indeed, there is a certain school of thought that claims that ’a
pair of bishops equals a rook and knight in the ending’. I’m not sure that this assertion can be
proven, but I decided to look at it from a statistical point of view.

From a sample of 68 high-level games in the NQE of rook and knight vs two bishops (this
time with players rated 2550 and above), there were 30 wins for the rook< and knight duo, 20
for the bishop pair, and 18 draws.

The number of wins achieved by the bishops seems quite high, which may reflect the
double-edged nature of this imbalance, but the overall percentage is a respectable 57% to
43%. We can interpret this as such:

a pair of bishops shouldn't be underestimated, but the rook and knight are still superior.

«Although I fortuitously saved this game it gave me the lasting impression that, ceteris paribus, rook and knight are superior to two bishops. Here, even with an extra pawn, Black was always somewhat worse. I’m also willing to bet that White’s chances are better than 57% (see the introduction to this chapter) in the initial position, but everyone is entitled to their opinion! My impression is that, in cases where the pawn structures are intact, the bishops can’t find enough targets and are thus inferior»