Sunday brain teaser review

3 comments

• Reply

  

  Yancey Ward says:

  August 7, 2011 at 8:32 pm

  Black has the rook’s pawn on the 2nd rank, thus is sure to lose even if we didn’t know it was white to play and mate. Seriously, though, the rook’s pawn does sort of constrain things for white since it threatens to pin anything on the first rank to the king, so I immediately looked to the various checks. The first one I looked at was Rd8+ to win black’s present queen for the rook, but this is going to be too slow since one of white’s pieces gets pinned and is useless:

  1. Rd8 Kd8 (Kc7 2.Rd7+-)
  2. Qb7 h1(Q)
  3. Qb8 Ke7
  4. Qc7 Ke8 and we can see the effect of the new black queen at h1- it pins the bishop, and white can’t bring his knight into action on the black king before he escapes to the safety of f7 or g8.

  Next, I looked at Qe6, and this one seems to be the right start, though I seem to be missing the short line described in the problem set up (Mate in 9:

  1. Qe6 Kb8 (Kc7 below)
  2. Rd8 Ka7
  3. Nb5 Qb5
  4. Bb5 h1(Q)
  5. Ka2

  And, now, white has the black king an inescapable net, but I find enough delaying sacrifices to push this out several moves beyond 9 total. The most resistant seems to be:

  5. …..Bd6
  6. Rd6 Qb7 (Qa8 7.Rd7+-)
  7. Ra6 Kb8

  White mates with queen and bishop on Qa6: [7. …Qa6 8.Qa6 Kb8 9.Qd6 Kb7 10.Bc6 etc. like the main line below] Continuing:

  8. Qd6 Kc8 (Qc7 9.Rb6 Kc8 10.Ba6)
  9. Rc6 Qc6
  10.Qc6 Kb8
  11.Qd6 Kb7 (Ka8 12.Bc6 Ka7 13.Qc7)
  12.Bc6 Kb6 (Ka6 13.Bd5 Kb5 14.Qc6)
  13.Bd5 Kb5 (Ka5 14.Bc4)
  14.Qc6 Ka5 (Kb4 15.Qb6#)
  15.Bc4 and there is no answer to all of the mating threats.

  Back at move 1, black could have played Kc7, but this still leads to mate:

  1. Qe6 Kc7
  2. Rd7 Kc8/b8
  3. Rb7 Kb7
  4. Ba6 and black will get mated in under 9 moves total as the knight comes into action with check if black plays Ka7 or Kc7, and on Ka8 or Kb8, the queen and bishop are sufficient to finish it in 2 more moves.

  So, where did I miss the short mate? Right now, I don’t have a clue.

• Reply

  

  Yancey Ward says:

  August 8, 2011 at 1:34 am

  I think I have it now, and it is a mate in 8, unless I am again overlooking something:

  1. Qe6 Kb8
  2. Rd8 Ka7
  3. Qe3

  The move I completely missed over and over. I even missed this move in the previous comment several moves later in that line. Continuing:

  3. …..Bc5 (Qb6 4.Rd7 still)
  4. Qc5 Qb6
  5. Rd7 Ka8 (Kb8 6.Qb6-7.Qa7/c7#)
  6. Qb6 Bc2 (else 7.Qa7#)
  7. Ka1 any
  8. Qa7#

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  Venky [ India - Chennai ] says:

  August 8, 2011 at 3:17 pm

  Hi Susan Polgar,

  Well,White wins the game.

  But for some reason,I couldn’t find 9 moves mate – To me,the mate happens in either 6/7/10 moves. [ I may have missed something,you guys are welcome to point it out ]

  Okay,my examples are as given below.

  Example one
  ===========
  1.Q*e6+ Kb8
  2.Rd8+ Ka7
  3.Rd7 B*c2+
  4.K*bc2 h1(Q)/N*f1
  5.Nb5+ Ka8
  6.Rd8+ Qb8
  7.Qa6++ Mate

  Example Two
  ===========
  1.Q*e6 Kb8
  2.Rd8+ Ka7
  3.Rd7 Q*Rd7
  4.Q*Qd7+ Kb6
  5.N*a4+ Ka5
  6.Qb5++ Mate

  Example Three
  =============
  1.Q*e6 Kb8
  2.Rd8+ Kc7
  3.Rd7+ Kc8
  4.R*Qb7 K*Rb7
  5.Bg2+ Kc7
  6.Nb5+ Kd8
  7.Q*f6+ Kc8
  8.Qc6+ Kd8
  9.Qc7+ Ke8
  10.Bc6++ Mate

  By
  Venky [ India – Chennai ]