PUBLICATION NOTE:
This article was published originally on The Chess Improver blog on 2016-10-18
I have reposted it here for reference.
Online voting chess is a nice challenge. Rules are very simple: two teams face each other in one game, each team can have as many members as possible, reflection time is 2 days per move and moves are selected by a majority of votes (each member has 1 vote). During the 2 days of reflection time each team discusses the position and merits of possible moves.
The selected voting team match is part of the World Cup IV semifinal and it is one where our team won an exchange early in the middle game and nursed the material advantage into present endgame. It is white to move and a heated discussion occured about the merits of choice A - 69.f5 ... versus choice B - 69.Rxh5 ... Now imagine you are white here in an OTB game. Time is of course a factor and you need to decide what to do. There's more than one way to skin a cat so it matters what you choose. I would imagine you could go with what you know or think you know best, right? Which one is that?
[Event "VC World Cup IV Semifinal"][Site "Chess.com"][Date "2016.01.06"][White "Team Canada"][Black "Team Bangladesh VC"][Result "*"][TimeControl "1 in 2 days"][SetUp "1"][FEN "8/8/6p1/4K2n/5P2/5k2/8/7R w - - 0 69"]
Going back to our debate, we had a good one going on. The first reactions were perfect:
wayne_thomas "69.f5 wins right away. If they take our pawn, they lose their knight and then their pawn."
MrWeakie "Either f5 or Rxh5 are absolute wins. After Rxh5, we Queen with check, and although it will take a few moves, K+Q vs. K+p on the 2nd rank is still a win. The technique involves checking with the Queen and slowly moving closer to the pawn, and then moving the king up. I would go with either move, the f5 version perhaps being less tedious than the Rxh5 version."
Wayne backed up his choice with 3 GM games where in 2 of them the Queen could not win vs the h-pawn.
MrWeakie continued with: "I agree that f5 is simplist and will vote accordingly. However, I challenge anyone to play this position with me and draw. I play white, you play black, and I will open with Rxh5!" and started to get some traction for his choice.
I won't bore you with the entire discussion; the idea is to see which one should you choose. Here are the merits and challenges of both:
Choice A - 69.f5 ...
1. It brings white immediate material advantage so it is easier to see
2. The Rook vs pawn endgame is an easy win because white captures the pawn very fast
[Event "VC World Cup IV Semifinal"][Site "Chess.com"][Date "2016.01.06"][White "Team Canada"][Black "Team Bangladesh VC"][Result "*"][TimeControl "1 in 2 days"][SetUp "1"][FEN "8/8/6p1/4K2n/5P2/5k2/8/7R w - - 0 69"] 69.f5 gxf5 (69...Ng3 70.fxg6 Nxh1 71.g7 Nf2 72.g8=Q Ng4+ and mate in 13) 70.Rxh5 f4 71.Rf5 Ke3 72.Rxf4 {and mate in 13}
Choice B - 69.Rxh5 ...
1. It gives back the material advantage
2. Reaching the Queen vs side pawn endgame requires calculation (simple one mind you) for the pawn race
3. Once in the Queen vs pawn endgame, white must use a harder technique (avoid the stalemate) to win
[Event "VC World Cup IV Semifinal"][Site "Chess.com"][Date "2016.01.06"][White "Team Canada"][Black "Team Bangladesh VC"][Result "*"][TimeControl "1 in 2 days"][SetUp "1"][FEN "8/8/6p1/4K2n/5P2/5k2/8/7R w - - 0 69"] 69.Rxh5 gxh5 70.f5 h4 71.f6 h3 72.f7 h2 73.f8=Q+ Kg2 {it is easy to analyse it up to here; now you need to get closer} 74.Qg7+ Kf2 75.Qh6 Kg1 76.Qe3+ Kf1 77.Qe4 Kg1 78.Qe1+ Kg2 79.Kf4 {lucky the King is close enough; in those 2 GM games selected by wayne the King was too far awa}y 79...h1=Q 80.Qe2+ Kg1 81.Kg3 {this is the mate in 3 winning position you need to know and have in mind when you choose}
Have you decided yet? Should I throw in a wrench in it and say the engines prefer 69.Rxh5 ... with mate in 15? The 69.f5 ... choice could go longer (mate in 17) as a battle of Queen vs Knight arises (see above). Does this make you change your mind? Remember, the clock is ticking... Oh, by the way our team chose A by a wide margin and team Bangladesh resigned!
This article was published originally on The Chess Improver blog on 2016-10-18
I have reposted it here for reference.
Online voting chess is a nice challenge. Rules are very simple: two teams face each other in one game, each team can have as many members as possible, reflection time is 2 days per move and moves are selected by a majority of votes (each member has 1 vote). During the 2 days of reflection time each team discusses the position and merits of possible moves.
The selected voting team match is part of the World Cup IV semifinal and it is one where our team won an exchange early in the middle game and nursed the material advantage into present endgame. It is white to move and a heated discussion occured about the merits of choice A - 69.f5 ... versus choice B - 69.Rxh5 ... Now imagine you are white here in an OTB game. Time is of course a factor and you need to decide what to do. There's more than one way to skin a cat so it matters what you choose. I would imagine you could go with what you know or think you know best, right? Which one is that?
[Event "VC World Cup IV Semifinal"][Site "Chess.com"][Date "2016.01.06"][White "Team Canada"][Black "Team Bangladesh VC"][Result "*"][TimeControl "1 in 2 days"][SetUp "1"][FEN "8/8/6p1/4K2n/5P2/5k2/8/7R w - - 0 69"]
Going back to our debate, we had a good one going on. The first reactions were perfect:
wayne_thomas "69.f5 wins right away. If they take our pawn, they lose their knight and then their pawn."
MrWeakie "Either f5 or Rxh5 are absolute wins. After Rxh5, we Queen with check, and although it will take a few moves, K+Q vs. K+p on the 2nd rank is still a win. The technique involves checking with the Queen and slowly moving closer to the pawn, and then moving the king up. I would go with either move, the f5 version perhaps being less tedious than the Rxh5 version."
Wayne backed up his choice with 3 GM games where in 2 of them the Queen could not win vs the h-pawn.
MrWeakie continued with: "I agree that f5 is simplist and will vote accordingly. However, I challenge anyone to play this position with me and draw. I play white, you play black, and I will open with Rxh5!" and started to get some traction for his choice.
I won't bore you with the entire discussion; the idea is to see which one should you choose. Here are the merits and challenges of both:
Choice A - 69.f5 ...
1. It brings white immediate material advantage so it is easier to see
2. The Rook vs pawn endgame is an easy win because white captures the pawn very fast
[Event "VC World Cup IV Semifinal"][Site "Chess.com"][Date "2016.01.06"][White "Team Canada"][Black "Team Bangladesh VC"][Result "*"][TimeControl "1 in 2 days"][SetUp "1"][FEN "8/8/6p1/4K2n/5P2/5k2/8/7R w - - 0 69"] 69.f5 gxf5 (69...Ng3 70.fxg6 Nxh1 71.g7 Nf2 72.g8=Q Ng4+ and mate in 13) 70.Rxh5 f4 71.Rf5 Ke3 72.Rxf4 {and mate in 13}
Choice B - 69.Rxh5 ...
1. It gives back the material advantage
2. Reaching the Queen vs side pawn endgame requires calculation (simple one mind you) for the pawn race
3. Once in the Queen vs pawn endgame, white must use a harder technique (avoid the stalemate) to win
[Event "VC World Cup IV Semifinal"][Site "Chess.com"][Date "2016.01.06"][White "Team Canada"][Black "Team Bangladesh VC"][Result "*"][TimeControl "1 in 2 days"][SetUp "1"][FEN "8/8/6p1/4K2n/5P2/5k2/8/7R w - - 0 69"] 69.Rxh5 gxh5 70.f5 h4 71.f6 h3 72.f7 h2 73.f8=Q+ Kg2 {it is easy to analyse it up to here; now you need to get closer} 74.Qg7+ Kf2 75.Qh6 Kg1 76.Qe3+ Kf1 77.Qe4 Kg1 78.Qe1+ Kg2 79.Kf4 {lucky the King is close enough; in those 2 GM games selected by wayne the King was too far awa}y 79...h1=Q 80.Qe2+ Kg1 81.Kg3 {this is the mate in 3 winning position you need to know and have in mind when you choose}
Have you decided yet? Should I throw in a wrench in it and say the engines prefer 69.Rxh5 ... with mate in 15? The 69.f5 ... choice could go longer (mate in 17) as a battle of Queen vs Knight arises (see above). Does this make you change your mind? Remember, the clock is ticking... Oh, by the way our team chose A by a wide margin and team Bangladesh resigned!