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Giovanni Vescovi vs Ranko Szuhanek
Wch U20 (1994), Matinhos BRA, rd 2, Sep-??
Sicilian Defense: Chekhover Variation (B53)  ·  1-0

ANALYSIS [x]

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Kibitzer's Corner
< Earlier Kibitzing  · PAGE 3 OF 3 ·  Later Kibitzing>
Sep-07-08  MostlyAverageJoe: <MostlyAverageJoe: I run out Qa1+ to a mate, too (in 16, I believe). Will post the line later.>

Well, here it is: <26...Qa1> results in a mate one move faster than <26. ... Rxc2>

<24. ... Bd5 25. Qxf6 Qxa2+ 26. Kc1 Qa1+> 27. Kd2 Rxc2+ 28. Ke3 Rc3+ 29. bxc3 Qxc3+ 30. Kf2 Qxf3+ 31. Ke1 Qc3+ 32. Rd2 Qc1+ 33. Kf2 Qxd2+ 34. Kg3 Qf4+ 35. Kg2 Qf3+ 36. Kh2 Qf4+ 37. Rg3 Qf2+ 38. Rg2 Qf4+ 39. Kh3 Qf3+ 40. Kh4 Qh3+ 41. Kxh3 Rc8 42. Qg7#

I think other engine see the (temporary) evaluations of positions where the black seems to have advantage and give up, e.g. in this intermediate position after 33. ... Qxd2+ :


click for larger view

black has five extra pawns, three of them passed, so static evaluation must be pretty high for the black (which is still 18 plies away from getting mated).

It is surprising that Rybka 3 is reported as not being able find the mate in in infinity analysis from the position after <24. ... Bd5>. This would be a second case I know of where Hiarcs finds a killer continuation missed by Rybka (another one is here: Yusupov vs J Nogueiras, 1985).

Sep-07-08  messachess: excellent problem-could be encountered in games at a lot of levels. Well, I got the fist move. I didn't see the theme with the Q going to h6. I was thinking that the B would be there for a back rank Q exchange for the R's somehow. 'Somehow,' that's the key word!
Sep-07-08
Premium Chessgames Member
  johnlspouge: Sunday (Insane): G Vescovi vs R Szuhanek, 1994 (21.?)

White to play and win.

Material: N for B. The Black Kg8 has 3 legal moves. White has a battery Rd1 and Qd2 on the semi-open d-file. Black has a threat on Nd4 requiring an active response. The Black K-side has dark-square weaknesses. Obviously, the White Bg5 emphasizes the weaknesses, but more subtly, Ng3 and Nd4 can also move to attack them. The White Rg1 faces Kg8, suggesting clearances on the g-file to remove Ng3, Pg4, Bg5, and Pg6. White can open the h-file at will with hxg6. Both Black Bs are loose and Nf6 is merely adequately guarded. White has a tender spot at Pc2, attacked by the battery Rc1 and Qc4, but the 2 White Rs defend the back rank against mate threats, so …Qxc2+ only nets Pc2. Similarly if Ng3 moves White must beware …Nxe4, but without a mate threat at c2, Qd2 protects Bg5.

Candidates (21.): hxg6, Ndf5, Ngf5

21.hxg6 (threatening 22.gxh7+ winning a P)

I gave an analysis as to why Black must recapture with a P, and within a human horizon, Toga readily rejects accepting the sacrificed Nd4 by 21...exd4. Toga also readily shows that 21...hxg6 is inferior to 21...fxg6. I thought the removal of Ph5 and Pf7 would increaes White's attacking chances.

As my candidates indicate, I was aware of the N sacrifices at f5. The fact that this is a puzzle, so something decisive "should" happen next, did not impress me. I would be curious if <anyone> could explain in human terms why they would play a N sacrifice over the board instead of opening the h-file first.

Some examination with Toga shows that counter to my expectation, the removal of Ph5 and Pf7 lessens White's attack because the Black Rs are then permitted a lateral defense of the 7-th rank.

Sep-07-08  Andrew Chapman: <Due to the treat Qxa2+ and afterwards Rxc2+ there is only one move, IMO:>I was wondering if Lost in Space was right about that being winning or drawing for black and then saw this by MAJ

<(+mate 19) 24... Bd5 25. Qxf6 Qxa2 26. Kc1 Rxc2 27. Kxc2 Rc8 28. Kd2 Qxb2 29. Ke1 Qc3 30. Rd2 Qc1 31. Ke2 Bc4 32. Kf2 Qxd2 33. Kg3 Qf4 34. Kh3 Qxf3 35. Kh2 Qf4 36. Rg3 Qf2 37. Rg2 Qf4 38. Kh3 Qe3 39. Rg3 Bf1 40. Kh4 Qg5 41. Kxg5 h6 42. Kxh6 Kf8 43. Qh8#> which is a pretty amazing line

Sep-07-08
Premium Chessgames Member
  johnlspouge: <<zenpharaohs> wrote: Interesting. My "solution" is:

21 hxg6 fxg6 22 Ngf5 gxf5 23 gxf5 Kf7 24 Bxf6 Bxf6

gaining a piece for a pawn. Rybka 3 agrees with it.>

Er, I like your initial move 21.hxg6, so don't think I am not on your side. It is White to move, however, and in this sequence, Black that gains the piece for the P, so I guess Rybka 3 is right.

In fact, according to Toga II 1.3.1, your variation does give White some pull. With best play,

[ply 18/84 time 03:33 value +0.41]

25.b3 Qxd4 26.Qh2 Qxg1 27.Rxg1 Rh8 28.Qd2 Be7 29.Qh6 Bf6 30.Rd1 Rcd8 31.a3 Ke7 32.Ka2 Kf7 33.Kb2 d5 34.Qh5+ Kf8 35.Rg1 dxe4

That is about all the pull for White I have seen on 21.hxg6. I have not seen any winning evaluations.

Sep-07-08  SouCapi: This one I got from the first move to the last one, piece of cake!! I must confess that took me about a minute to see it, Ok, I'm a bit rusty, too old for this game and thirty years not playing a tournament game. Any how, I took as I personal challenge: if this Brazilian patzer (capivara) Vescovi can find it OTB, I, another brazilian patzer, can do it "blindfold". So I did it.
Sep-07-08  zenpharaohs: It seems that a lot of people are looking into the line

21 Ngf5 gxf5

but I think black should play 21 ... Kf8 instead of gxf5.

If you get the game line to 24 Nf5, then indeed the better response is 24 ... Bd5 but black is still lost; even though there is a very long continuation where black nearly gains a draw at several points, presumably black would not resign until about move 40.

I'm definitely wondering what is up with Rybka 3 though. It is a lot stronger player than any of my other engines but it's not as easy to use for analysis.

Sep-07-08  zenpharaohs: johnlspouge: "Er, I like your initial move 21.hxg6, so don't think I am not on your side. It is White to move, however, and in this sequence, Black that gains the piece for the P, so I guess Rybka 3 is right."

I have found why the engines have trouble with this position - what happens is that 24 ... Qe6 is not as good as 24 ... Bd5. But the continuation from 24 ... Bd5 has a very long sequence where black goes on a king hunt that very neary swindles a draw - there are several moves where white has only one move which keeps his threat alive:

25 Qxf6 Qxa2+ tally ho!
26 Kc1 Rxc2+
27 Kxc2 Rc8+
28 Kd2 Qxb2+
29 Ke1

The king has had no choice

29 ... Qc3+
30 Rd2

This is forced to avoid the draw

30 ... Qc1+

Here white has an option of two moves:

31 Kf2 Qxd2+
32 Kg3 Qf4+
33 Kh3

otherwise draw

33 ... Qxf3+
34 Kh4

otherwise black wins

34 ... Qxf2+
35 Rg3

otherwise draw

35 ... Qh2+
36 Kg5

otherwise draw

37 ... Qd2+
38 Re3

otherwise draw

39 ... Qxe3+

here black has been able to force the exchange of the rook for the queen, with check, and in such a way that white's mate threat is disrupted

40 Nxe3 Be6

However, now white immediately imposes another mate threat

41 Qh6

and indeed the game is lost in this line. In the other line

31 Ke2 Bc4+
32 Kf2

otherwise lose

32 ... Qxd2+
33 Kg3 Qf4+
34 Kh3

otherwise lose or draw

34 ... Qxf3+
35 Kh2 Qf4+
36 Rg3

(or 36 Kh1 which is an even longer tightrope, otherwise draw)

36 ... Qd2+
37 Rg2 Qf4+
38 Kh3

otherwise draw

38 ... Qe3+

this offers the queen to disrupt the mate, it is quicker for white to decline

39 Rg3 Bf1+
40 Kh4

otherwise draw

40 ... Qxg3+
41 Nxg3

again, black is now lost.

The point of these tightrope variations is that although black doesn't actually win, it is a tightrope where white must play very precisely to avoid losing or drawing.

Now to the human player, it's tricky, but to the computer, having a lot of lines which become draws is a sure way to burn up a ton of computer cycles and not be able to rule in or out continuations, so the search cannot get very deep.

So it's not surprising to me that engines can choke on some of the lines here.

And as far as for a human playing over the board? I doubt that the "correct" move (21 Ngf5) would win if black was any of stronger engines mentioned in this kibitzing - unless the human was a strong GM, otherwise too much time would get lost avoiding the traps.

Sep-07-08
Premium Chessgames Member
  johnlspouge: <<zenpharaohs> wrote: [snip] I have found why the engines have trouble with this position>

I agree with your implication that engines are not totally trustworthy here, although I now believe that 21.Ngf5 is indeed the "right" move.

I am dumbfounded that anyone could find 21.Ngf5 over the board when a good "safe" alternative like 21.hxg6 is available.

Sep-07-08  zenpharaohs: johnlspouge: "I agree with your implication that engines are not totally trustworthy here, although I now believe that 21.Ngf5 is indeed the "right" move.

I am dumbfounded that anyone could find 21.Ngf5 over the board when a good "safe" alternative like 21.hxg6 is available."

I have also found that using Rybka 3 in the Shredder interface (my usual interface) is probably not the best way to use Rybka 3; I have just started analyzing this problem in Aquarium and although it is still preferring 21 hxg6 in the deep analysis mode, it was able to recognize 21 Ngf5 as a good move very quickly in game analysis mode, and it has already annotated 24 ... Qe6?! and 24 ... Bd5 !?

I suppose I will have to learn how to use Aquarium if I want to use Rybka 3 for reliable analysis.

Sep-07-08  MostlyAverageJoe: <zenpharaohs: .... I think black should play 21 ... Kf8 instead of gxf5>

Correct. My take on the best play for both sides is:

21. Ngf5 Kf8 22. hxg6 hxg6 23. Nxe7 Kxe7 24. Nf5 gxf5 25. gxf5 Qxc2 26. Qxc2 Rxc2

If you want to plug it into Rybka and analyze for mistakes, it might confirm it.

<zenpharaohs: I have just started analyzing this problem in Aquarium and although it is still preferring 21 hxg6 in the deep analysis mode, it was able to recognize 21 Ngf5 as a good move very quickly in game analysis mode, and it has already annotated 24 ... Qe6?! and 24 ... Bd5 !?>

Wow again. In backslide (which it should be using for game analysis), Rybka really should see that both moves lead to a forced mate, and that no exclamation points are deserved for either. Curious.

Sep-07-08
Premium Chessgames Member
  whiteshark: I'll check it tomorrow. The cheque is in the post.
Sep-08-08
Premium Chessgames Member
  kevin86: The idea of this one is to get the pawns off the g-file. The sac removes black's and the combination following takes away white's.

The big,bad rook then dominates and the end is very near

Sep-12-08  patzer2: For the Sunday September 7, 2008 puzzle solution, White initiates a deep and decisive attack with 21. Ngf5!! to weaken and exploit Black's castled position.
Dec-05-21  mel gibson: I wasn't sure but I thought it was one of the Knights to f5.

Stockfish 14 says:

21. Ngf5

(21. Ngf5 (♘g3-f5 g6xf5 ♗g5xf6 ♗e7xf6 ♕d2-h6 f5xe4 ♘d4-f5 ♗b7-d5 ♖d1xd5 ♕c4xc2+ ♔b1-a1 ♖d8-d7 f3xe4 ♖d7-c7 ♖d5-d1 ♗f6-h8 ♕h6-g5+ ♔g8-f8 a2-a3 f7-f6 ♕g5-h6+ ♔f8-g8 ♕h6-e3 ♕c2-c5 ♕e3-d2 b5-b4 a3xb4 ♕c5-c2 ♕d2xc2 ♖c7xc2 ♘f5-e7+ ♔g8-g7 ♘e7xc8 ♖c2xc8 ♖d1xd6 ♖c8-b8 g4-g5 f6xg5 ♖g1xg5+ ♔g7-f7 ♖d6-h6 ♗h8-f6 ♖g5-f5 ♖b8-b6 ♖h6xh7+ ♔f7-g8 ♖h7-d7 ♖b6-e6 ♔a1-a2 ♗f6-e7 ♔a2-b3 ♗e7-f6 ♖d7-a7 ♗f6-e7 ♖a7-b7 ♗e7-f6 ♔b3-c4 ♗f6-d8 ♖b7-b8 ♖e6-e8 ♔c4-d5) +8.10/35 256)

score for White +8.10 depth 35.

Dec-05-21  Brenin: I saw 21 Ngf5 gxf5 22 Bxf6 Bxf6 23 Qh6 fxe4 24 Nf5 Qe6 25 g5 Bg8 26 g6, but wasn't sure what Black could do next, or whether I had missed alternative Black responses. Looking now at the kibitzing from 2008, it seems that there was plenty to miss, including the unlikely-looking 24 ... Bd5.
Dec-05-21  nalinw: The first move is obvious - what makes the problem difficult is selecting the best follow up moves - like taking on f6 first - and very importantly Qh6 before opening g file.

However perhaps not insane ...

Dec-05-21
Premium Chessgames Member
  An Englishman: Good Evening: Too insane for me. And a humbling 4/7 for the week. On to Monday!
Dec-05-21
Premium Chessgames Member
  agb2002: White has a bishop and a knight for the bishop pair.

Black threatens Qxd4 and exd4.

A quick scan yields lines like 21.Ngf5 gxf5 22.gxf5 Qxd4 23.Bxf6+ Kf8 24.Qh6+ Ke8 25.Rxd4.

Or 22... exd4 23.Bh6+ (23.Bxf6+ Kf8 24.Rg8+ Kxg8 25.Qh6 Qxc2+ 26.Ka1 Qxd1+ and mate next) 23... Kh8 24.Qg5 Qxc2+ 25.Ka1 Qxd1+ 26.Rxd1 Rg8 27.Qd2 looks good for White in spite of the material deficit.

Or 22... Kf8 23.Ne6+ fxe6 24.Bxf6 Bxf6 25.Qh6+ Ke7 26.Qxh7+ and mate in two.

I'd probably play 21.Ngf5 and hope the best.

Dec-05-21
Premium Chessgames Member
  agb2002: I had the impression that opening the g-file was more important than placing the other knight on f5. Actually, 25... Ke7 is a blunder in my last line when 25... Ke8 26.Qxf6 exf5 allows Black to hold. This means that 22.Nxf5, followed by Bxf6, Qh6, g5, etc., is far preferable to 22.gxf5, as the game shows.
Dec-05-21
Premium Chessgames Member
  Teyss: The key to the puzzle which I missed is figuring to open the g file despite the 4 pieces in the way. Then the dilemma 21.Ngf5 or Nef5 is solved and 22.Bxf6 makes sense, which at first doesn't since the B looks like an essential piece.
Dec-05-21  Pawn Slayer: "SouCapi: This one I got from the first move to the last one, piece of cake!! I must confess that took me about a minute to see it, Ok, I'm a bit rusty, too old for this game and thirty years not playing a tournament game. Any how, I took as I personal challenge: if this Brazilian patzer (capivara) Vescovi can find it OTB, I, another brazilian patzer, can do it "blindfold". So I did it."

Please post your address and I'll send a builder round to widen all your doors so you can get your head through.

Dec-05-21
Premium Chessgames Member
  Teyss: <Pawn Slayer> 😂 Indeed provoking on a Sunday, even 13 years ago.
Or was it a case of irony alert? 🤔
Dec-05-21
Premium Chessgames Member
  chrisowen: Loophole it u ai v Ngf5 honors hangtight ado adour it v i no adagio niggle loophole v it u ai v maybe it whir dojo it jacque v i quintessential flicks flippers plays it girly cue it v amy goodness blights vintly it when part it z coffin x udder delight grovels handout v feints heff vintly eg flush axioms v ie it aloe it jet to honour it ok hug it i a v need close it garrulous creed it i vent carter v i x foodbin i clobber it i bah humbug abridge clocks c hog it if i v pilots backed it hang i mc eg hop boi v blubber it i v hi c changed it ho do c fog i v it dan c he vintly frugal z it sh a con it can dre on ar v cobble cockle fees it i give bouncing it v i fo go v candy o fig v it higgly piggly gritz fox garcon covids it esconced it a v figure vintly cranked it over biz it hood fang it heck baldtouch x flung do ta bite v it cods order axe i thigh it all v liberty cos ie v it viaduct it sarnie d5 openfile it rank ills v i gods no wood of a lie it i v house no fun tn loose it i v any cream fox ridge it how it to finish Ngf5 cub!
Dec-05-21  Rama: Darn, I liked Nef5.
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