The Troitzky Line

1) Analyse von Carlsen,M (2772) - Wang Yue (2736) [D17]
2nd Pearl Spring Nanjing CHN (8), 06.10.2009

Karsten Mueller

 

The Troitzky line An important variation in the analysis of the game Magnus Carlsen-Wang Yue ended in the following position with two knights against two pawns, which is won although two knights alone can't checkmate. Due to several requests, I would like to consider this problem once more in detail:
65.Nf4! It is of vital importance to safely block the f-pawn on the Troitzky line a4-b6-c5-d4-e4-f5-g6-h4. This always wins, however, possibly not with regard to the 50-moves rule. Taking this into account, the new line is a5, c5, d5, e5, f5, h5 , always with positions existing on the b- and g-file which can't be won within 50 moves. But those are very rare. The additional black d-pawn plays no part here since it can easily be raked in which, after blockading the f-pawn, is White's next goal now:
65...Kb4 66.Kc2 Kc5 67.Nf7 Kc4 68.Ne5+ Kb5 69.Kd3 Kc5 70.Nc4 Kb4 71.Kxd4 Now the black king must be forced into a corner in which White can checkmate it. In this very favourable case, White principally can checkmate in all four corners since the blockade knight on f4 is placed quite centrally. However, there are examples where this is different. There is one rule in particular: if the pawn has passed the Troitzky line, then there are drawing and losing zones for the defending king. The drawing zones can be safe edges or corners, but not necessarily. In the present case, of course there is no salvation. The defending king will try to finally escape in the direction of the north-eastern corner in order to survive as long as possible. Most favourable for him would be squares like g5, g4 or f3, yet in this case he can't get there if White doesn't let him.
71...Ka4 72.Ne5 Kb5 73.Ned3 Kc6 [If the defender tries to escape towards the south, play might continue as follows: 73...Ka4 74.Kc4 Ka3?! 75.Nc5 Kb2 76.Kd3 Kc1 77.Na4 Kd1 Now follows a typical technique, known as 'Henry's side check': 78.Nb2+ presenting Black the choice in which corner he wants to get checkmated: 78...Ke1 (78...Kc1 79.Kc3 Kb1 80.Nbd3 Ka2 81.Kb4 Kb1 82.Kb3 Ka1 83.Nd5 f4 84.Nc3 f3 85.Nb4 f2 86.Nc2# ) 79.Ke3 Kf1 80.Nbd3 Kg1 81.Ne1 Kf1 82.Neg2 Kg1 83.Ke2 Kh2 84.Kf3 Kg1 85.Ne3 Kh2 86.Kf2 Kh1 87.Kg3 Kg1 88.Ne2+ Kh1 89.Nd1 f4+ 90.Kh3 f3 91.Nf2# ]
74.Kc4 Kd6 75.Kb5 Ke7 76.Ne5 Kd6 77.Nf3 Since the knights are forming a barrier, now the king can advance. This knights' placement is often very effective at least against central or bishop pawns.
77...Kd7 78.Kc5 Kc7 79.Nd4 Kc8 80.Kc6 Kd8 [80...Kb8?! runs into the direct 81.Nb5 Kc8 82.Ne6 f4 83.Nd6+ Kb8 84.Kb6 f3 85.Nc7 f2 86.Na6+ Ka8 87.Nb5 f1Q 88.Nbc7# ]
81.Nde6+ Ke7 82.Kc7 Kf7 83.Kd7 Since the knights are not able to lose tempi, it is very important to choose the right squares with the king. Triangle manoeuvres often play a vital part in this endgame too.
83...Kf6 84.Kd6 Kf7 85.Nd4 Ke8 [After 85...Kf6 86.Nf3 Kf7 87.Kd7 Kf6 the white king bypasses his counterpart with 88.Ke8 Kg7 89.Ke7 Kg8 90.Nd4 Kg7 91.Nde6+ Kh7 92.Kf7 Kh6 93.Kf6 Kh7 94.Kg5 Kg8 95.Kg6 Kh8 96.Nd5 f4 97.Nf6 f3 98.Ng5 f2 99.Nf7# ]
86.Nc6 Kf7 87.Ke5 Kf8 88.Kf6 Ke8 89.Ke6 Kf8 90.Ne5 Ke8 91.Nf7 Kf8 92.Nd6 Kg7 93.Ke7 Kh7 94.Kf7 Kh6 95.Kf6 Kh7 96.Kg5 Kg7 and now finally the moment has come where the blockade knight initiates the final attack:
97.Ne6+ Kh7 98.Ne8 f4 99.Nf6+ Kh8 100.Kg6 f3 101.Ng5 f2 102.Nf7# For those who want to delve even deeper into this fascinating territory, I would like to indicate some sources in the following: A. Troitzky, Collection of Chess Studies, 1937 Richard Forster, Late Knight column 24, Archive of www.chesscafe.com, April 2000, Late Knights' Tango: The Troitzky Endgame Karsten Müller, Endgame Corner column 35 and 36, Archive of www.chesscafe.com, November and December 2003, The damned pawn Balashov, Prandstetter, Basic Endgames, Prague Chess Agency 1992, S.55-65 Cheron, Text and handbook of endgames, Volume 2, 2nd edition, Verlag Das Schach Archiv 1964, p. 220–250 Speelman, Tisdall, Wade, Batsford Chess Endings, Batsford 1993, p. 112–115 1-0