Thursday, October 05, 2006

Rook vs Pawns, 10/05

I've been studying Rook vs Pawn endings. Would you guess, in 54% of games the pawn suffices for a draw?! Read on to learn the secrets.

1. The Force Field

In the simplest case, you prevent the enemy king from accompanying his pawn.

If his pawn advances alone, your rook picks him off. For example, 1.Rg5 a5 2.Rf5 a4 3.Rg5 a3 4.Rg3! a2 5.Ra2 a1=Q 6.Rxa1 wins.

If his pawn doesn't advance, your king strolls to the a1 promotion square, and again it's an easy win for White. Eg, 1.Kh7, 2.Kh6, 3.Kh5, 4.Kg4, 5.Kf3, etc.

This technique works best against rook pawns, but only if the enemy king can be prevented from reaching his own fourth rank.

2. Entombing

If the enemy king steps on the same file as his rook pawn, you can trap him there.

1.Kc4 Ka3 2.Rb3+! Ka4 3.Rb5 Ka3 4.Rxa5+ wins.

3. The Tempo Count

The Tempo Count is a general tool you'll use in 80% of your Rook vs Pawn endings.

Count how many tempos it will take for the weaker side to promote. The king needs 2 tempos to reach a2. The pawn needs 4 tempos to reach b1.

Now, count how many tempos it will take for the stronger side to protect b1. The king needs 3 tempos to reach c2. The rook needs 1 tempo to reach g1.

Since the stronger side can protect b1 in 4 tempos, but the weaker side needs 6 tempos to promote, this game is a win for the stronger side. Tempo counting is faster and easier than thinking "I will move here, then he will move there..."

4. Checking for a Tempo

Sometimes you're one or two tempos away from winning.

The weaker side is 3 tempos from promoting. The stronger side is 3 tempos away from protecting b1, but the enemy king blocks the way.

However, after 1.Rc7+! Kb2 the weaker side is now 4 tempos away from promoting because his own king blocks his pawn. White can still defend b1 in only 3 tempos, and so wins easily.

5. Knight Underpromotion

What if you're on the weaker side, and your opponent threatens mate? Black's situation looks desperate.

1...c1=N+!, and it's a drawn Rook vs Knight ending.

6. The Cold Shoulder

The weaker side also has a trick to gain free tempos.

White needs 2 tempos to guard the promotion square: Kg2, Kf2. Black needs 3 tempos to promote: Ke3, Kd2, e1=Q is a loss for Black--too slow.

However, Kf3! draws by simultaneously moving Black's king closer to the promotion square while blocking out White's king.

7. Barbier,Saavedra 1895

This is a rare and fascinating study. White to win?! The natural moves 1.c7 Rd6+ 2.Kc5? Rd2! only draw.

I found a stronger sequence: 1.c7 Rd6+ 2.Kb5! Rd5+ 3.Kb4 Rd4+ 4.Kb3 Rd3+ 5. Kc2... but Black still draws if he spots 5.Rd4! 6.c8=Q Rc4+ 7.Qxc4 1/2-1/2. Barbier knew this.

However, the monk Saavedra invented an incredible continuation! 6.c8=R!! Ra4 7.Kb3 Kb1 8.Kxa4 and White wins.

8. Connected Pawns

A rook can even stop connected pawns all by itself--as long as it acts before they both reach the sixth rank.

The secret is to get behind the lead pawn. In this diagram, Rg6 then Rg4! wins.

9. Split Pawns

A lone rook can't stop a king and split pawns unless four or more files separate them.

In the diagram, if Black plays 1...Ke2? or 1...Kg2?, White plays 2.Rxa2! and draws.

With these tricks up your sleeve, you'll win or draw more than your fair share of Rook vs Pawn endings.   :)

10 comments:

transformation said...

1340!!!!!!!!!
86.0!

believe you me, higher percentage does boast ratings, just not as fast, but more surely! we loose points for slowness, but how few we loose!

now for your 1370, soon my friend!
dk

SamuraiPawn said...

Great post! My endgame knowledge is close to nothing and these things make you realise what a vast landscape chess really is.

/Chris

Bob said...

Very good post indeed and the rule of counting tempi is well worth remembering!

My own CTS results now after 400 problems

1258 .... BUT ... 84.3%

My rating is holding constant now, rather than dropping, but the percentage correct, is creeping up almost every day.

Finally ... it seems sometimes I post as "Bob" and sometimes as "Bungertingbaloner." It doesn't seem worth the effort to straighten it out.

likesforests said...

samuraipawn, glad you like. Even a really simple endgame like K+R vs K+P is complex enough that GMs make mistakes. I'm going to be a lot less worried about losing the next time I have to sacrifice my rook.

After looking at 40 games that ended with K+R vs K+P, I added the Cold Shoulder technique. The weaker side often uses it to win an extra tempo or two (and score a draw).

likesforests said...

Bob, ahh! I didn't connect that the two names were the same person. I'm glad your rating has stabilized and your accuracy is moving up. It sounds like you've already studied some endgames. I learned a few basics themes from Bruce Pandolfini's Endgame Course, but now I'm ready to master them ala Dvoretsky.

transformation said...

likeforests:
elevated ratings at CTS are angonistic to increased percentage success, i feel--surely not as a necessary condition, but probable.

i am sure that i will experience this soon. i want 87% more than 1550 or 1560, so must refocus...

for the last 203 problems, i should have 14.5 failed, not 18 to get to my goal in the next 7,977 tries as previously indicated. so in the next 203 tries [29 sets of 14 minus 203 recently = 203), i can only allow 11 failed or 11f/192s = 203 @ 94.6% and i have not had one session or set of sessions like that in weeks, not at 200+ tries any way.

so the drive to 87% cannot happen except in concret form, and 'the journey of a thousand miles begins with a single step', or 'why put off for tomorrow what can be done today?'

bob:
always nice to see you. we all enjoy your grace and good chear. question: is it possible that if you are 1260 at CTS that dvoretsky's endgame manual is a bit extended? seirawans winning chess endings or chernevs practical chess endings or averbakhs endings, essential knowledge in their entirety or in any combination done slowly and with care, i feel strongly, will be worth more than the razzle dazzle of dvoretsky.

you have to walk before you can run.

even i am waiting for dvoretsky, kind of like an endgame virginity. i must find the right .... first .... and premature efforts damaging if not misguided, IMHO.

Bob said...

Transformation, et al: there is some confusion, I fear ... or perhaps a mis-statement on my part. In any event, I am not pursuing Dvoretsky's endgame book; I don't own it, even (as yet). At my far more modest skill level I am working through Pandolfini's Endgame Course, which should occupy me for some little while. Dvoretsky's books on --- well, virtually anything --- are some significant distance away.

King of the Spill said...

Great post!

Phil said...

Hi,

I'm in a game right now on RedHotPawn...

http://www.redhotpawn.com/gameanalysis/boardhistory.php?gameid=5003876

I'm white, with only a rook, my friend is black and is advancing his sole pawn.

My king is blocked from nearing the pawn by black's king.

Can I win from this position? Or is the best I can hope for a draw?

likesforests said...

I can't answer you directly due to the rules of the site, "(b) While a game is in progress you may not refer to chess engines, chess computers or be assisted by a third party. Endgame tablebases may not be consulted during play but you may reference books, databases consisting of previously played games between human players, and other pre-existing research materials."

I have written two more articles on Rook vs Pawn which go a bit deeper into it, and if you study them, the truth of this position should become clear. I would be happy to discuss specifics after the game.

Rook vs Pawns II
Rook vs Pawns III