Quote:
Originally Posted by PyramidScheme
RB vs R is winnable???!??!
Wikipedia says:
Quote:
It is generally a theoretical draw, but the rook and bishop have good winning chances in practice because the defense is difficult. Ulf Andersson won the position twice within a year, once against a grandmaster and once against a candidate grandmaster; and grandmaster Keith Arkell has won it 18 times out of 18 (Hawkins 2012:193). In positions that have a forced win, up to 59 moves are required (Speelman, Tisdall & Wade 1993:382). Tony Kosten has seen the endgame many times in master games, with the stronger side almost always winning (Kosten 1987:11). Pal Benko called this the "headache ending" (Benko 2007:154).
Computer endgame tablebases show that 40.1% of the legal positions with this material are theoretical wins, but that includes many unnatural positions that are unlikely to occur in games. Edmar Mednis estimated that less than 4% of starting positions that occur in games are theoretical wins (Mednis 1996:80).
Quote:
Originally Posted by QuantumCage
So Caruana didn't know how to win RB V R in a theoretical won position. At least it seemed he could just in time win the rook before the 50 move rule. Btw one can not trust Nalimov in these things as it doesn't take Fide rules into account.
I haven't checked the positions before move 99 (am too lazy), but Fabi indeed got a theoretically won position after Peter's 102... Ka4? Fabi could have forced Peter to give the rook up (or be mated) on (or by) move 116, just before the 50-move rule would have triggered a draw.
This is confirmed by
a tablebase site that includes DTZ50 (DTZ50 TBs calculate the depth to 'zeroing', i.e. a piece capture, a pawn move, a mate or a draw claim possibility, with the 50-move rule taken into account).
Here's the link to look up the position after move 102.
And it's indeed a textbook Philidor position, but the winning technique is rather complicated; fortunately, it has been covered in
a Youtube videos by NM Alex Richter
Looking up the preceding position (just before Svidler's mistake) reveals that he had as many as 7 drawing moves (incl. Rh2 that would have been losing if Caruana had 4 more moves available before the 50-move role coming into play).
Last edited by coon74; 03-27-2016 at 06:08 PM.