The creation of the previous post forced me to create a framework. When I now encounter a problem, I can relate it to the framework. Which helps to let it stick long enough until the next repetition of a problem of similar theme.
I could find the general strategy (Lucena) for a KRpKR ending in Troyis mode in about two weeks.
The strategy to promote a rook pawn can't be found in Troyis mode, since it is too complicated and counter intuitive. I looked at a few video's and now the general idea of promoting the rook pawn is clear.
That's how it works. You start with passive study (the don't DIY part). Then you make it your own by actively trying to imitate the solution in practice.
That is what makes learning problematic. You have to change from passive mode to active mode. Both states are addictive. But if you study passively alone, it doesn't stick. While if you study actively alone, you have to invent everything yourself, which doesn't work either. Starting to absorb matter passive and digest it active requires a disciplined mind.
Sometimes positions are hard to explain. Take for instance the following problem. You are inclined to think that it is easy to switch to the standard position here. Yet the line to the win is incomprehendsible thin. If I could explain every best move from this line, I would probably make a big step forward.
You can find the problem here. I think that it is very important to be able to explain the best line of play since that is fundamental understanding you will need time and again.
Or take the following diagram. Hopefully is this is such rare bird that I don't need it in practice, but it gives an idea of how complicated it can be. The best move in the following diagram is Rd6.
I really don't have the slightest idea why Rd6 is best. What does it accomplish? It looks like a tempo move. But white can make a tempo move too.
You can find the problem here.
Luckily it's not the only winning move, but why is it the best?
I think these two positions are less complicated than you think.
ReplyDeletea) The pawn is under attack and there are only three ways to defend it.
1.Kd5 allows the defending king to get in front of the pawn with 1...Ke7. Also it's going backwards which looks funny in principle.
1.Rd5 is a really awkward place to put the rook. I can't explain exactly why Black can now draw in all variations, but this is clearly not White's promising move.
1.d5 moves the pawn forward, continues to keep Black's king away, and leaves the rook available to interpose against checks from the side. If any move works, it's 98% likely to be this one.
b) You don't need to care about 1...Rd6 being the fastest tablebase win; 1...h2 is a textbook win. The White king is cut off by four ranks, so Black has time to get his rook to g1, wriggle his king out through g2 and then either go in front of or behind the White king depending on whether it is on e2 or e3. See http://en.wikipedia.org/wiki/Rook_and_pawn_versus_rook_endgame#King_in_front_of_pawn for example. This is a standard maneuver worth knowing.
@dfan,
ReplyDeleteI can live with b). It is a textbook win, and that is good enough for practical play. I just was amazed that 1. ... h2 is mate in 39 while 1. ... Rd6 is mate in 29. Just wondering what's so special about Rd6.
With a) the problem is not the first move alone. The whole line to promotion is very critical. Often there is only one move. When there seem to be more correct moves, they transpose to the main line. I don't understand why this line is so critical. I'm missing something fundamentally here.
Usually these kind of lines are much less critical.
Hi Temposchlucker. I took a look at your second position and to sate your curiosity here's what I've discovered:
ReplyDeleteBasically, the reason why you play Rd6 first is to prevent the white rook from going to the sixth rank, since in the ensuing KQvKR endgame, by accident of geometry it is a lot harder to win the rook when it is on a6 than when it's on a7.
Here are the two lines:
1... Rd6 2. Kc1 h2 3. Rg7 Ra6 4. Kd2 Ra1 5. Ke3 Rg1 6. Rd7 Kg2 7. Rg7+ Kf1 8. Rf7+ Ke1 9. Ra7 Rg3+ 10. Kf4 Rf3+ 11. Kxf3 (M15) (best 11. Ke4(M20)) h1=Q+ This is a M14.
1... h2 2. Rg6 Ra7 3. Kd2 Ra1 4. Ke3 Rg1 5. Rd6 Kg2 6. Rg6+ Kf1 7. Rf6+ Ke1 8. Ra6 Rg3+ 9. Kf4 Rf3+ (M32) (best 9... Rg6 (M31)) 10. Kxf3 h1=Q+ This is a M31.
Kind of illustrates how silly theory mode can be. :)
@Zwisch,
ReplyDeletethanks! That is very clarifying!
It would be more clear to show the "distance to promotion". In that case Rd6 is spilling 1 move.