Jun0916   greed and death: 31. Rh8+ just screams to be played, but I thought the follow up would be 32. Rh1+ on instinct. 

Jun0916
  Penguincw: Another Korchnoi puzzle. Can't wait to see the Monday puzzle. But yeah, 31.Rh8+ Kxh8 I got, but did not see 32.Qf7. It can be hard seeing these quiet moves. The other line I tried was the losing 31.Qxf7+ Kxf7 32.Rh7+, trying to trap the king with a mating net using the 2 rooks, but the king escapes with 32...Ke8. 

Jun0916
  FSR: Why not 31.Rh7? 

Jun0916
  al wazir: My solution was 31. Rh7. If 31...Kxh7, then 32. Qxf7+ Kh6/Kh8 33. Rh1+ Qh5 34. Rxh5+ gxh5 35. Qh7#. If instead black plays 31...Rf7, then 32. Rch1 f5 (with any other move black must give up a ♕ for a ♖ to avoid mate) 33. Rh8+ Kf7 34. R1h7+ Ke8 35. Rxf8+ Bxf8 36. Rxb7, and white is up a piece. If 31...f5, then 32. exf6 Qxf6 33. Qxf6 Bxf6 34. Rxb7. 

Jun0916   TeaChess: For 31. Rh7, Bf6 is what I forget to calculate. 

Jun0916   EIDorado: @TeaChess I don't see any problem with 31. Rh7 Bf6 31. Rh1 . The Bishop is lost for sure, and maybe more 

Jun0916   stst: Either Rh8+ direct or Rh7, same effect... after which Qxf7
Note also the Black Q is essentially trapped, so after 31.Rh7 KxR, 32.Qxf7+ Kh8, 33. f4 and the Black Q is forced to go onto hfile, 34.Rh1+ will take it.
The thing is keep the area f8f2h1h8 "airtight" .... can't allow the K to escape (e.g. via f8 to e8.) 

Jun0916   stst: <Why not 31.Rh7>
Yup, Rh7 actually better than Rh8, tightening the rope, and leave one for Qxf7+ (in the game, it's Qxf7, but not + at the same time, that's the difference!! ==> that allows the Black Rd1... dissipating White's tension!! 

Jun0916
  Once: Fritzie prefers 31. Rh8+ to 31. Rh7, although the margin isn't great. The eval is currently 5.00 for Rh8+ and +3.93 for Rh7. It seems that Rh7 is a little more complicated because it is not a check and so allows Black more time to try to defend. He might try to block the f file with Bf6 or f5. Interestingly, there is a hybrid of the two moves. After 31. Rh8+ if Black declines the rook with 31...Kg7, white offers it again with 32. Rh7+ click for larger viewNow Black is in a world of hurt as 32...Kxh7 allows 33. Qxf7+ and white gets to turbocharge his attack by playing it with check. And any move other than 32...Kxh7 allows Qxf7# 31. Rh8+ was my pick because it was a check. I must admit I didn't even look at 31. Rh7, but I think it works too. 

Jun0916   gofer: The start is easy, white gives up a rook to get avery strong attack. The difficulty is that
black can immediately give back the rook advantage and at that point there was a lot to
work out, but finally (with the bits on the board) I realised that playing f4 separates
Qg4 from the defence of Be7. At that point the combinations became clear... <31 Rh8+ ...>
The acceptance of the rook sacrifice is forced...
31 ... Kg7
32 Rh7+ Kxh7 (Kf8/Kg8 Qxf7#)
33 Qxf7+ Kh8
34 Rh1+ Qh4 (Qh5 35 Rxh5+ gxh5 36 Qh7#)
35 Rxh4+ Bxh4
36 Bxg6 mating
<31 ... Kxh8>
<32 Qxf7 ...>
White threatens Rh1+ with the continuations given above, I think there are only two defences
worth mentioning...
32 ... Rd1
33 Rxd1 Rxd1
34 Nxd1
click for larger viewBlack's position is in tatters, White is about to play f4 winning Be7 and there is nothing black
can do about it because moving the queen loses Be7 anyway and moving Be7 loses Bb7! Taking Pe5
allows Qe8+ taking the bishop without losing tempo!
<32 ... Rxe4>
<33 Rh1+ ...>
click for larger viewBlocking the h file with the queen loses quickly.
33 ... Qh5
34 Rxh5+ gxh5
35 Qxe7
click for larger viewBlocking the h file with the rook loses quickly too!
33 ... Rh4
34 Rxh4+ Qxh4
35 gxh4 c5+
36 Kg3
click for larger view~~~
Yep!
I see a few are wondering about <31 Rh7> as an alternative and I was too, but I discarded it as I couldn't see how to
make progress after the "simple" <31 ... f5> which causes loads of complications! click for larger view Thanks <Once> for the Fritz point count. 

Jun0916   jffun1958: "Victor the Terrible" R.I.P.
I won't forget you. 

Jun0916   Razgriz: Heh, I played with the idea of the rook sac but after a rather lackluster 23 moves after, I didn't see that the queen will win a both bishop while keeping the Black King in check. 

Jun0916
  morfishine: The ole rooksac, Qxf7 trick. Can't get enough of this theme 

Jun0916   mel gibson: nice puzzle.
I saw it quickly. 

Jun0916
  agb2002: White has a bishop and a knight for the bishop pair and a pawn. Black can attack the pawn on e5 with Nd7 and Bf8g7.
The obvious moves are 31.Rh7 and 31.Rh8+.
In the case of 31.Rh7:
A) 31... Kxh7 32.Qxf7+ Kh8 (32... Kh6 33.Rh7+ and 34.Qxg6#) 33.Rh1+ Qh4 (33... Qh5 34.Rxh5+ gxh5 35.Qh7#) 34.Rxh4+ Bxh4 35.Bxg6 Rd7 36.Qf8#. B) 31... Rf8 32.Rhh1 wins.
C) 31... f5 32.Rhh1 is similar to B (32... fxe4 33.Rh8+ and 34.R1h7#). 
In the case of 31.Rh8+ Kxh8 (31... Kg7 32.Rh7+ Kxh7 32... Kg8 33.Qxf7# 33.Qxf7+ transposes to A above) 32.Qxf7: A) 32... Rf8 33.Rh1+ Qh4 (33... Qh5 34.Rxh5+ gxh5 35.Qh7#) 34.Rxh4+ Bxh4 35.Qxf8+ Kh7 36.Qf7+ Kh8 (36... Kh6 37.Qxg6#) 37.Bxg6 and mate soon. B) 32... Rd1 33.Rxd1 (33.Nxd1 Qxc1) 33... Rxd1 34.Nxd1 Na6 (due to 35.Qe8+ and 36.Qxb8) 35.Bxg6 Qh6 36.Qxe7 Qxg6 37.Qxb7 Qe4+ 38.f3 Qc2+ 39.Nf2 +  [N+P]. C) 32... Qh5 33.Bxg6 Qh6 34.Rh1 Qxh1+ 35.Kxh1 and mate soon. 
I think I'd play 31.Rh8+. 

Jun0916
  patzer2: For today's Thursday puzzle (31. ?) in honor of Korchnoi, I managed to correctly play guess the move with 31. Rh1+! Kxh1 32. Qxf7 . However, after 32...Rd1 I went for 33. Nxd1 (diagram below) click for larger viewHere (diagram above) I was hoping for 33...Qxc1?? when 34. Qxg6 forces mate in four moves. If in this position (diagram above) Black plays the strongest defense 33...Rf8, my movebymove look with Deep Fritz 15 indicates White wins after 34. Qxe6 Kg7 35. Nc5 Bc8 36. Qxc8 Bxc5 (36... Rxc8 37. Ne6+ ) 37. Qe6 Bd4 38. Rc4 c5 39. Rc2 Rf7 40. Bd5 Rf8 41. f4 Qd8 42. Be4 Qb6 43. Qe7+ Rf7 44. Qg5 Qe6 45. Nf2 Nc6 46. f5 Rxf5 (46... Qxe5 47. Qxg6+ Kf8 48. Qxc6) 47. Bxf5 Qxf5 48. Qxf5 gxf5 49. Nd3 Kf7 50. Kf3 (+3.60 @ 22 depth, Deep Fritz 15). Of course Korchnoi's sound winning reply 33. Rxd1 (+5.73 @ 25 depth, Komodo 8) is a stronger and easier win than the 33. Nxd1 Rf8 34. Qe6 alternative win analyzed here. It's difficult to find improvements in Black's play in this game. My own preference would be to start early in the opening. Instead of 8...Bb7, allowing 9. e4! (+0.35 @ 28 depth, Stockfish 150516), the computer choice 8...Ba6 = (0.22 @ 35 depth, Komdo 9.3) looks better. Earlier in the opening, instead of 6...c6 7. 00 = to , I prefer opening things up with 6...dxc4 = as in A Giri vs Topalov, 2016. 

Jun0916
  beenthere240: Classic problem in reversal of move order. First idea: 31. Rh8+ looks good, but Rh1+ follow up leads nowhere. Second idea 31. Qxf7+ looks interesting, but follow up Rh7≠ doesn't work. So try a third idea: switch move order and combine. Now 31. Rh8+ is followed by 32. Qxf7, threatening mate next move. But wait, can't black block the rook? Yes, but he has to give back the sacrificed rook leaving white with a huge attack. Qe8 is a nice finesse, forcing the black king to the 7th rank where the g pawn will be taken with check, stopping the black queen from coming to the rescue. Not that I saw any of this of course. 

Jun0916
  kevin86: White corners the king, then sets out to capture him. 

Jun0916   YouRang: Pffft. I spent my time fixating on <31.Ng4>, thinking black could do little to stop Nh6+, which would threaten Qxf7+ .
click for larger view
I figured that black would bolster the defense of Pf7 with <31...Rf8>, and then comes <32.Nh6+ Kg7 33.Nxf7!>
click for larger view
If black takes the N with <32...Rxf7>, then <33.Rh7+ Kxh7 34.Qxf7+> with Rh1+ and a win coming next. Alas, I overlooked black's best defense, which I'll leave as a puzzle for anyone interested (see first diagram above): <31...? Black to play and not lose quite so fast> ~~~~
I'm starting to get that sinking feeling that I probably would lose against Korchnoi. So in his honor, here is a quote from him: <Skeletons of mice are often to be found in coconuts, for it is easier to get in, slim and greedy, than to get out, appeased but fat.> I'm sure this applies to chess somehow, but only after you get into Tal's deep dark forest where 2+2=5. 

Jun0916   posoo: WOWOWOW NOBBICUS really dos kno how to find all da ansurs dosunt he?! 

Jun0916   CHESSTTCAMPS: Material is essentially even, with black having the bishop pair. Black owns the open dfile with the rook battery, but white's ownership of the hfile is more important, given that the black kingside is so poorly defended. It quickly becomes apparent that f7 is weak  31.Rh7! goes straight for the target, threatening immediate mate: A. 31... Kxh7 32.Qxf7+ Kh6 (Kh8 33.Rh1+ Qh5 34.Rxh5+ gxh5 35.Qh7#) 33.Rh1+ Qh4/h5 34.Qxg6# B. 31... Rf8 32.Rch1 f5 (f6 33.Rxe7 fxe5 34.Rh8+ forces mate) 33.exf6 e.p. Bxf6 34.Rh8+!! (simplest) Bxh8 35.Rxh8+ Kxh8 36.Qxf8+ Kh7 37.Qf7+ Kh8 38.Bxg6 Qh6 (forced) 39.Qxb7 Qxg6 40.Qxb8+ Kf7/g7/h7 41.Qxa7+ followed by 42.Qxd4 leaves white ahead by two knights and several pawns. B.1. 33... Rxf6 34.Rh8+ Kf7 35.R1h7#
B.2. 33... Qxf6 34.Rh8+! Kf7 (Qxh8 35.Rxh8+ Kxh8 36.Qh6+ forces mate) 35.Bxg6+! Kxg6 36.Qh5+ Kg7 37.Qh8# C.31... f6 32.Rxe7 (or R1h1) wins
D.31... f5 32.R1h1 Bf6 33.exf6 fxe4 34.Rg7+ Kf8 35.Rh8# After starting down B (and trying to decide between 33.Rxb7 and Rh8+), I realized that a simpler, alternative candidate would be 31.Rh8+ Kxh8 (Kg7 32.Rh7+ forces mate as in variation A above) 32.Qxf7 Rxe4 33.Rh1+ Qh5 34.Rxh5+ gxh5 35.Qxe7 wins more material... Time for review... 

Jun0916   devere: According to the silicon fish (depth 40) there are 4 winning moves: 31.Rh8+ +7.25
31.Nc5 +6.65
31.Rh7 +5.30
31.Ng4 +2.23
I looked first at Rh7, was soon satisfied that it won, and never got around to looking at the other possibilities until I fired up the fish. Nice game by the late great Viktor Korchnoi. 

Jun0916   King.Arthur.Brazil: Again I made the same analysis and mistakes of YOURANG. I played Ng4 and tried to find what else. The simple and best Rh8+ and once kxh8 you understand everything. 
