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Oscar Humberto Castro Rojas vs Borislav Ivkov
Sao Paulo (1978), Sao Paulo BRA, rd 5, May-??
Vienna Game: Vienna Gambit. Breyer Variation (C29)  ·  1-0
ANALYSIS [x]

FEN COPIED

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Kibitzer's Corner
< Earlier Kibitzing  · PAGE 2 OF 2 ·  Later Kibitzing>
May-12-15  mihinduep: Have just joined the site. How wonderful it would have been if the last two moves of each player was highlighted by coloring. Then it is easy for amateurs and beginners like myself to follow and learn the game.
May-12-15  TheaN: Whoops. I did look at Nxg7 and Nh6+ which both seem to win but aren't as convincing, and because of that decided on the sketchy 34.Nd7?!: this is suboptimal after 34....Qd7, now 35.Rh6! still wins but if you don't see the pattern at all, white has a tough game after 35.Qg6?! Nf8! . I missed Nf8, otherwise this would work too.

Seems difficult for a Tuesday.

May-12-15
Premium Chessgames Member
  gawain: Surprisingly difficult. Kept looking for dramatic moves. Frustrated, I set the puzzle aside for a little while. When I returned to it I noticed 34 Rh6, attacking that pesky black knight. This seems to work!
May-12-15  bachiller: 34.- Rh6!

A move worthy of an Oscar.

May-12-15  starry2013: No, couldn't see Rh6, whether I was looking for a mate or just to gain a big advantage.
May-12-15  dfcx: I am going with 34.Rh6, the defender of g7.
34...Kf7 35.Nd6+ royal fork.
34...Kf8 35.Rxe6 Qxe6 36.Qxg7+ Ke8 37.Nd6+ Kd8 38.Qf8+ 34...Other moves 35.Rxe6
May-12-15
Premium Chessgames Member
  patzer2: One interesting tactical position after the demolition 20. Bxh6!! gxh6 21. Qg6+! is the possibility 21...Kf8 (diagram below):


click for larger view

Here White wins with the surprise clearance 22. Ng3! due to the threat of Rf1 with a mating attack (e.g. 22. Ng3! Ke7 24. Qg7+! Ke8 25. Rf1! ).

May-12-15
Premium Chessgames Member
  kevin86: Missed this one! The quiet move pulls the keystone of black's position.
May-12-15
Premium Chessgames Member
  thegoodanarchist: Definitely too hard for a Tuesday, as many others have noted.
May-12-15
Premium Chessgames Member
  Once: Woo - that took a while to see. Like many others, I kept looking for forcing moves instead of the GOOTy 34. Rh6. Found it eventually.

Here's the position after the aforementioned GOOT:


click for larger view

The Black knight on e6 is attacked by the Rh6. It can't run away without running into Qxg7#. And the black queen's protection is useless because Rxe6 removes the defender of g7.

We also have to work out what happens if Black plays Kf7 or Kf8.

Tuff Choosday.

May-12-15  BOSTER: <Dr.J: Ivkov missed 35.Nd6+>.

I am not sure that Ivkov could see 35.Nd6+ after white sacr. the bishop 20.Bxh6 for 3 pawns (not once),what was in <fashion> in 70-80 y., leaving the black king naked in the pos. where to find the <escape> to the west it was not so easy.

May-12-15  Tiggler: 34. Rh6 and the knight cannot be defended (34. ..Kf7 35 Nd6+).

34. ..Kf8 also avoids the immediate mate, but also loses the black Q:

35. Nxg7 Nxg7 36. Rh8+

May-12-15
Premium Chessgames Member
  Check It Out: I didn't get this one. I think I've been trained to look for forcing moves, especially on Mondays and Tuesdays, and 34.Rh6 is not a forcing move. A good reminder that not all strong puzzle moves are checks or sacrifices.
May-12-15
Premium Chessgames Member
  Domdaniel: <Once> -- < Like many others, I kept looking for forcing moves ...>

Yes, of course I know what you mean: you were looking for a dramatic sacrifice (as was I). But surely the very pretty Rh6 *is* a forcing move -- after all, it wins quickly.

When we talk about forcing moves, do we mean only checks and sacs?

May-12-15  Tiggler: <Domdaniel>:<When we talk about forcing moves, do we mean only checks and sacs?>

According to Houdini, the puzzle position is +M15, with first move Rh6. I guess that is forcing.

The line continues:
34. Rh6 Kf8 +M14 (34. .. Kf7 35. Nd6+
+M10 (35. Rg6 +M9)) (34. .. Qf7 35. Rxe6 +M10) 35. Rxe6 (35. Nxg7 Nxg7 36. Rh8+ Kf7 37. Qf3+ Ke7 38. Qf6+ Kd7 39. Qd6+ Kc8 40. Qc6+ Kb8 41. Rxe8+ Nxe8 42. h5 +M10) 35. .. Qxe6 +M13 36. Qxg7+ Ke8 37. Nd6+ Kd8 +M11 38. Qf8+ Kd7 39. Qxa8 Qg6 40. Qc8+ Ke7 41. Nf5+ Kf7 42. Qd7+ Kg8 43. Ne7+ Kh7 44. Nxg6+ Kxg6 45. e6 Kh6 46. Qf7 a6 47. h5 Kg5 48. Qg6#

May-12-15  MagnusVerMagnus: Nice puzzle, this would have been easy if I did not know it was suppose to be "easy" But once you can not find he "forced" win in 3 moves you look for the weak link, the Ne6 is holding the position together and it must be ellimitated. Nice puzzle.
May-12-15  Pedro Fernandez: I didn't see the move <Sokrates>, however 34.Na6+ must also win due the extraordinary potential that the white kingside pawns have.
May-12-15  Pedro Fernandez: As always <chrisowen> making a long analysis which it is hard to decode, but after all he is our strongest chess player; I never have had some doubt at respect.
May-12-15  Pedro Fernandez: Hi Tiggler, what's up my friend!
May-12-15  Tiggler: <Pedro Fernandez: Hi Tiggler, what's up my friend!> Hello. Just visiting POTD while waiting for some real excitement to begin again.
May-12-15  Tiggler: <MagnusVerMagnus: Nice puzzle, this would have been easy if I did not know it was suppose to be "easy">

And a lot easier if you did not know it was a puzzle. A rare example where the correct move would be easier to find over the board than in the setting of a puzzle.

May-13-15
Premium Chessgames Member
  Once: <domdaniel> Interesting question. It may be another instance of chess terminology being inexact.

I think when we say "forcing" we largely mean "immediately forcing". A check is certainly a forcing move because the opponent is compelled to get out of check. A capture also has a degree of compulsion to recover the lost material.

34. Rh6 is forcing in that it leads to a forced win. But it is not immediately obvious that it does. At first glance it only threatens a knight which appears to be adequately defended. It contains the threat of Rxe6/Qxg7#, but until we analyse a bit more deeply we don't know whether black can defend against this threat. After all, he does start the puzzle position a piece up. If he could defend g7 then he might let his Ne6 go.

That's why I coined the term GOOT - a threat which isn't immediately forcing but which the opponent can't wriggle out of.

May-13-15
Premium Chessgames Member
  Check It Out: Goot one, <Once>. <Dom>, our posts seem so similar.

An interesting conversation on the definition of a "forcing move".

May-13-15  starry2013: Well Tiggler...

A computer will no doubt define forcing differently to an average human chessplayer (which is I guess what Mondays and Tuesdays are normally geared to).

May-13-15  Tiggler: <starry2013: Well Tiggler...

A computer will no doubt define forcing differently to an average human chessplayer>

My previous post about +M15 was a little misleading. I don't think Houdini can find this line on its own from the puzzle position without help. I won't here go into the methods that a human can use to help an engine, however.

A line that goes in the least number of moves against best defense to checkmate is not a "computer line". It is the chess truth about a position and does not depend on the method used to find it.

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