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The same grandmaster from An overconfident grandmaster decides to avenge his loss and prepares for rematch. He ends up in a winning position once again. He decided to place a bet again. He gives the player two consecutive moves, if he wins the game, he wins the bet, loses if he does not.

Unlike the last time, he includes two restrictions, a bishop cannot be moved when making two consecutive moves, and a single piece cannot be moved twice. enter image description here

Should the player accept the bet? You're white.

Bonus question: Should you accept the bet if drawing or winning the game wins you the bet?

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  • $\begingroup$ Must the player use the 2 consecutive moves from this position, or can he wait until a later point in the game? $\endgroup$
    – JLee
    Oct 5, 2022 at 10:58
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    $\begingroup$ Which player has the two consecutive moves (i.e. the one we help)? Which color are they? $\endgroup$
    – user79541
    Oct 5, 2022 at 13:06
  • $\begingroup$ The player with the losing position is white, who is also the only player for whom "can't move a bishop" is actually a restriction at the moment. So I assume it's "white to make two consecutive moves and win, if possible". $\endgroup$
    – Gareth McCaughan
    Oct 5, 2022 at 13:09
  • $\begingroup$ This might be a spoiler, so I'll mask it: rot13(Qbrf gur "ur" va "vs ur jvaf gur tnzr, ur jvaf gur org, ybfrf vs ur qbrf abg" ersre gb gur cynlre be gur tenaqznfgre)? $\endgroup$
    – xyldke
    Oct 5, 2022 at 13:24
  • $\begingroup$ It's white to move, sorry for inconvenience. $\endgroup$
    – I'm Nobody
    Oct 5, 2022 at 14:20

1 Answer 1

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In this particular position, having an extra free move with the restrictions given (i.e., no Rc1xc6xc7) does not seem enough for White to win the game:

  • Two different pieces must be played and not the bishop, so one of the two moves has to be made by a pawn or by the king, which can neither capture nor threaten anything at the moment.

  • If the rook capture on c6, it will be taken next move. It cannot threaten much either, e.g. Rb1 aims at b7 but doesn't lead anywhere after 1...Nxa5

  • Meanwhile, Black has a decisive material advantage, a mass a passed pawns on the queenside and a threat against the immobile White bishop.

However, White has a nice trick based on a pin.

By playing 1.Rxc6 and 1.f4 (1.Rxc6 and 1.h4 works as well, the point of the pawn move being to prevent ...g5), they force Black to answer 1...bc6 (otherwise the extra rook will win easily) when 2.Bc3! is deadly:

The queenside pawn mass is discoordinated and cannot disturb the bishop, the Nf6 is pinned, the black King cannot move either without dropping the knight, ...g5 loses to fg5 Kg6 gf6.

So he can only play pointless queenside pawn moves, when White wins either by zugzwang after centralizing the king, or more directly by picking the knight after h3-g4-g5, keeping the one pawn they need securely on f6.

Black might try 1...Nd5, but even a grandmaster will not save the rook-down endgame after e.g. 2.Rc1.

Per @I'mNobody in the comments, a computer analysis shows that Black can actually save a draw with 1...bc6 2.Bc3 Kf8! 3.Bxf6 Ke8 4.Kf2 Kd7, when White won't be able to eliminate all the queenside pawns nor place the opponent king in zugzwang: the game is a draw with best play.

It means that taking the bet is actually a gamble by White, since they won't be able to win if the grandmaster finds the saving plan - which they might if they don't lose hope, at least by elimination process.

Bonus question: If a draw is enough, the player with White should definitely accept the bet and play 1.Rxc6 and 1.f4/h4.

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  • $\begingroup$ Great, exactly the solution I intended to see but unfortunately it's not rot13(Jva sbe juvgr rira nsgre oynpxf cnja ner uvtuyl hapbbeqvangrq, gur xvat pna fheeraqre gur xavtug ol cynlvat xs8, naq nggrzcg gb ernpu gur zvqqyr bs gur snfgre guna juvgr naq tnva pbageby bs gur oynpx cnjaf. Gur erfhygvat cbfvgvba, nsgre u4 be s4 vf n qenj (Fgbpxsvfu rinyhngvba ng qrcgu 60: 0.0) So that's why I added the bonus question, and I have no "no-computers" tag as well so its perfectly reasonable to use a computer. $\endgroup$
    – I'm Nobody
    Oct 6, 2022 at 19:48

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