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Subject: how do you mate?

I know how to mate w/ a king & rook Vs. a king, but I couldn't figure out how to mate w/ a king, rook, & knight Vs. king & rook? The opponenet kept adverting it easily, I'm an avg. rated player & so was my opponent, but is the only way to mate in that scenerio entirely dependant on an opponents blunder/bad move or can it be forced regardless? Any links or help would be direly appreciated.

board #2482938 <--the mate scenerio in question.



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RN vs R is

usually a draw, but if the defending king is near the edge a win is possible. If the defending king is in the corner, the chances of winning are much greater. RN vs RP has better winning chances in many cases.

All this according to Karsten Muller and Frank Lamprecht, Fundamental Chess Endings.



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Technical draw after 52. Rxg5

The K+R+N vs K+R is generally always a technical draw, unless the opponent blunders into a K-R skewer or K-R fork, or gives away the R, or very specific positions exist. There are 5 piece endgame tablebases available that can confirm this.

I backed up your position to before the 5 piece endgame. Unfortunately, 51. Rg6 was a blunder for you, as it vacated the 7th rank and your b7 pawn, allowing a pawn trade. A knight up may seem like a knight up and a win, but that's not the case here.

Rather, virtually any R move away from his K but remaining along the 7th rank would have been a winner.

For example,

51. Rc7 threatens Rc8+ producing check while simultaneously defending the b8 promotion square, and after the black K moves to the 7th rank, b8=Q--effectively your opponent will have to trade his R for the new Q (so really a R for P trade), leaving you with a R and N versus a lone pawn, which you can quickly gobble up and move on to a classic K+R mate (don't even need the N).

He effectively has no defensible options.

He cannot move his R off the b-file or mate will follow quickly in one or two moves depending on where his R was moved to.

He cannot even prolong the agony of promotion and trade by checking you as both check squares (b2 and e5) are covered by your knight.

51. ... g4 simply moves his P closer to your K for later capture after he trades the R for the new Q.

Any K move in response to 51. Rc7 leads to 52. Rc8+ followed by 53. b8=Q Rxb8 54. Rxb8 and a quick win to follow.

He could capture the pawn at b7 with his R, followed by 52. Rxb7, but that only hastens his doom as his K would be trapped on the 8th rank. Your K comes in for the kill a few moves later.

Not knowing your strategy I can only speculate and that you may have thought that being a knight ahead could win. However, consider that you cannot win with a knight alone, so since you both have very mobile Rs, they almost balance each other out; the less mobile knight simply can't do much. It is too easy for him to move his R off to an edge and then throw repeated checks at you. Eventually the checks will cease (K approached the R, or is shielded by his N or R), but you only have a couple of moves to try anything, before he's moved his R to an edge, followed by a bunch of checks again, and so on and so on until 50 moves after the last capture the game's a draw.

Similarly R+B vs. R are nearly always technical draws since the bishop can't control the opposite color squares.

Even R+P vs. R are often technical draws. It generally depends on the your K position relative to your P. Your K must nearly always be ahead of the P (that is, closer to the promotion square than your P). It can be very similar to K+P vs. K positions.

So before reaching or forcing a particular endgame, make sure that you can complete it as desired. A prime opportunity was lost in this game. Hopefully you won't make that mistake again. Good luck!



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super thank you both

I should of gone 51. Rc7, I remember considering it (I've even won many games in that fashion w/ less simple scenerios!), but I Know what happened cuz also remember thinking that if I did that followed by 52. Rc8+ then the king would flee and I'd immediately lose my pawn Rxb7! my logic was flawed, how embarressing, a lesson well learned. thanx



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R+N vs R

This is the ending that bogg and I played out in an otb event one time. The game lasted 8 hours and over 105 moves, ending in a draw. (It could not be adjourned due to being in the next to last round of the event.) He is an otb Master besides one at GK, and I was "A" or Expert then, I dont recall which. But he had the upperhand of it. Yet I entered it deliberately, sac'g my last minor piece to get to that pawnless ending, being the best chance I had to hold the game.
The funny part of it was, some 30+ moves into this ending phase I did move poorly (which in Chess parlance, is known as "being a Fish", if you've heard the term :)and walked into a lengthy forcing sequence where the better side could win. But apparently the fatigue factor after 7 hours and 3 prior rounds of play was enough that both players missed that one fatal position when it occurred. And then it was immediately gone like a will-o-the-wisp, typical of such endings where there is no second chance to win them. }8-)
punkusmartyrus It sounds like you've gotten good feedback on it.
It is a difficult ending to win, even if it happens to Be winnable. And as you see, even for highly rated players. I would speculate it should seldom be winnable when your opp enters it forcibly, if he is a passable engame player ... as bogg told me, he was trying hard to avoid getting into it. And he is the one who pointed out after the game that I had shook hands with Chessic Death and only walked away by a hair, as I hadn't seen that actual win , although things were definately feeling a bit sticky at that time ! :)
Regards, Craig



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John Nunn says...

One of my all time favorite books... "Secrets of Pawnless Endings" by John Nunn. This is an excellent book looking at almost every combination of pieces vs. other pieces. The chapters are very VERY informative. I have used this book frequently here on GK to help me determine wether to go for a certain ending or not.

Anyway, here is what GM Nunn says in Chapter 6 R+N v R

This ending is in general a draw. White has far fewer winning chances than in the ending of R+B v R and in practice the ending is usually agreed drawn immediately. In all top level practical examples I have encountered, there was no occasion when the superior side won.

He goes on to give many fine examples on how to win, how to draw it, etc.. etc... Like I said, it is a truly well-written book. Very advanced but written in plain language. If anyone knows GM Nunn, they know he is a theoretician!




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Some analysis...

I like this game. Very well played, until the ending (just kidding).

But this was one interesting game!! A very instructive end-game. Like a see-saw, back and forth!

38 ...g5? allows white to win with
39.Nxf5 Kg8
40.Rg6 Kf8
41.Nxe3 gf
42.Rf6 Ke7

but white plays...

...instead which allows Black to equalize with 39 ...f4! However, black decides on...
39 ...hg?

After this, white is winning up untill move 49.Nc4??

49.Rh7! would have won...
49 .... Rb2
50.Kd3 g4
51.Rh8 Ke7
52.b8 Rxb8
53.Rxb8 and this is a known win.

However, even after the error of 49.Nc4 Black decides he wants to miss his last chance to draw with the obvious
49 ....Kxd7!

But decides to try 49 ...Rb5? What was he thinking?

Whites turn to miss...
50.Nd6!! is another win...
50 ....Kxd7
51.Nxb5 and the pawn can not be stopped! But instead....

50.Rg7 is played which is not all that bad but the follow up...

allows the game to be a draw.

Any questions, comments, or refutations to the analysis is welcomed.



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As a general rule...

(And I should say GENERAL), in *pawnless* endgames you need to be have a material advantage of at least a rook in order to win. Thus K vs. K+B+N is a (headache-inducing) win, but K+N vs. K+R is generally a draw.

As I say this, I feel I'm being sacked by the irony. Not long ago, in a game in which it was clear I was being outplayed in every way, I made a couple of sacrifices to get to a "drawn" K+B vs. K+R endgame. Good strategy, but in my haste to do this I left my king in the wrong corner, and the rest is history.

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