# The Grey Labyrinth is a collection of puzzles, riddles, mind games, paradoxes and other intellectually challenging diversions. Related topics: puzzle games, logic puzzles, lateral thinking puzzles, philosophy, mind benders, brain teasers, word problems, conundrums, 3d puzzles, spatial reasoning, intelligence tests, mathematical diversions, paradoxes, physics problems, reasoning, math, science.

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Coyote

 Posted: Sat Apr 13, 2002 9:52 pm    Post subject: 1 The Nowotny Theme is one of the simplest strategic chess problem ideas. A Black Rook and Black Bishop each guard a different crucial square (or line). If the two lines of attack intersect, White can play a piece onto the intersection square to interfere with both lines. Whichever of the two Black pieces captures the White piece, the other will be blocked, and White can take advantage of it. Okay...I guess that explanation didn't sound too simple, but maybe this example will help: Mate in Two Moves B. Barnes, 1965 Chess Board `7q/4r1bp/1B6/3N4/8/1Q1N1P2/3k2K1/1b1BR3` The Black Rook guards the line e6-e1, and the Black Bishop guards the line f6-a1. If White plays 1.Re5, both these lines are interfered with and White threatens both 2.Ba5++ and 2.Be3++. If the Black rook captures White's rook, White can still play 2.Ba5. If the Black bishop captures, 2.Be3 works. Of course, Black may have other defenses available that counter both these threats. 1...Bc2, for example, which is easily countered by 2.Qxc2++, or 1...Bxd3, which is met with... Well, actually, that works pretty well as a defense! No two-move mate here, in spite of the Nowotny Interference. But there's another white piece that can move to the crucial e5 square: after 1.Ne5, White again takes advantage of the double interference of BR and BB by threatening 2.Qc3 or 2.Qe3. Again, there are a couple of Black moves that defeat both threats, but now the alternate defenses, 1...Kc1 or 1...Kxe1, can both be answered, by 2.Be3 and 2.Ba5 respectively.* I hope that explanation helped out a little, because now we're going to turn things up a notch or two: Mate in Two Moves J. C. van Gool, 1978 Chess Board `q7/bbRB3r/r5Rp/2P1N1p1/QNn2kP1/2BP1P1K/3P2P1/5n2` I don't think I'll be giving too much away here by stating flat out that the crucial square is c6, because no less than seven White pieces can move to this square! Which White piece should you decide to move to c6, and what are the correct Black refutations to the six wrong decisions? -------------------------- *A nice little grace-note here: the two White mates are the same moves as were threatened in the unsuccesful first attempt! ------------------ The sun never sets on the Labyrinth
CrystyB
Misunderstood Guy

 Posted: Sat Apr 13, 2002 10:17 pm    Post subject: 2 The standard solution says the highest ranking piece gets sacrificed. Qc6. That enables either Rf6 or Nd5. Now for the other six moves... I am in a hurry and am sorry can't figure them out. [This message has been edited by CrystyB (edited 04-13-2002 06:18 PM).]
cubestudent
3D Member

 Posted: Sun Apr 14, 2002 12:20 am    Post subject: 3 grr. i messed up. but it gave me: if white trys the g6 rook, black should respond with Qg8 [This message has been edited by cubestudent (edited 04-14-2002 01:09 AM).]
sweetwater
Male Member

 Posted: Sun Apr 14, 2002 8:56 am    Post subject: 4 1. Rcc6, threatening Nd5 or Rgf6 (or g3, if N on f1 moves). If 1. ... Bxc6 2. Rf6# If 1. ... Rxc6 2. Nd5# If 1. ... Nce3 2. Nd5# If 1. ... Nfe3 2. g3# The other six moves can be refuted as follows: 1. Qc6 Nce3 2. Nbc6 Ng3 3. c6 Bd4 4. Bc6 Qd8 5. Nec6 Nfe3 6. Rgc6 Qg8
Coyote

 Posted: Sun Apr 14, 2002 9:27 am    Post subject: 5 Correct on all points, of course. Well done! And now, to give cubestudent another shot, here's one where White must choose from one of four possible Nowotny interferences, each on a different square: Mate in Two Moves C. Mansfield, 1956 Chess Board `8/3Rp3/2K1P3/3B2Bb/4p2r/nppk3r/5PPb/NN2Q2n`
ctrlaltdel
Member of the Daedalians

 Posted: Sun Apr 14, 2002 10:24 am    Post subject: 6 f3! if ...Rxf3 2.Qd1 mate if ...exf3 2.Qe3 mate if ...Bxf3 2.Qe3 mate if ...Kd4 2.Qxc3 mate or maybe i missed something...
Coyote

 Posted: Sun Apr 14, 2002 10:21 pm    Post subject: 7 Welll...maybe! There's two other Black defenses that defeat both the threatened mates. Also, you didn't supply refutations (if any) for the other three possible pawn moves. Minor quibble, that, unless of course you picked the wrong one for your answer!
CrystyB
Misunderstood Guy

 Posted: Sun Apr 14, 2002 10:31 pm    Post subject: 8 "if any" You didn't ask for any refutations... Well i tried the first one offline and settled for the Nbc6. (btw why isn't Nbc6 Nfe3 g3 a mate?) I bettter start STUDYING chess before i attempt any puzzles. Only playng experience is not enough - i am failing to see LOTS of moves... ow and what other three pawn moves? What would f4 accomplish??? another edit. "g4"? Q threatens either e3# or xe4#. [This message has been edited by CrystyB (edited 04-14-2002 06:36 PM).]
Coyote

 Posted: Sun Apr 14, 2002 10:56 pm    Post subject: 9 Originally posted by CrystyB:"if any" You didn't ask for any refutations... Guilty as charged. As this was a follow-up puzzle to the first one, I'd meant to imply that the same conditions held, i.e. 'Find the correct White move and the Black moves that defeat the other White attempts.' My use of the parenthetical 'if any' was mainly to tease ctrlaltdel with the nagging doubt that his answer might not have been the correct one. though, in fact, it was. As for 1.f4: It threatens both 2.Qxe4# and 2.Bxb3# (taking advantage of the interferences on the h4R and h2B, respectively). [This message has been edited by Coyote (edited 04-14-2002 06:58 PM).]
CrystyB
Misunderstood Guy

 Posted: Sun Apr 14, 2002 11:09 pm    Post subject: 10 bah... Bxb3!!! It could be argues that since there is no more single destination square for many pieces to attempt a Nowotny, not necessarily all other particular options apply...
ctrlaltdel
Member of the Daedalians

 Posted: Mon Apr 15, 2002 6:34 am    Post subject: 11 ahh, i see coyote, the knight can stop me... tell me more crystyB... 1. Bxb3+ Bd6 - where's the mate in one? or im still missing something... grrr
CrystyB
Misunderstood Guy

 Posted: Mon Apr 15, 2002 11:00 pm    Post subject: 12 but Nc4 can't stop Qxe4 can it? Or Nxb1 Qe3... DAMN i don't even know the names [/edit] No ctrlaltdel, i was just giving proof to me not noticing all possibilities. I was just upset of the Bishop sidestepping to make room read all the invisible text Coyote left - it says you were right in your move , amongst other things [This message has been edited by CrystyB (edited 04-16-2002 07:06 PM).]
ctrlaltdel
Member of the Daedalians

 Posted: Mon Apr 15, 2002 11:53 pm    Post subject: 13 ahhh now i see. i was blind but now i see. i really thought there was a defence for black, especially after not considering the knight on a3. it kept me puzzled for a while - if black's second move would be Nc4 trying to protect the vital e3 square and blocking the mate on d1 at the same time then white has to play Bxe4#. for a strange reason i did not see this one - which explains my confusion. i think its the nicest of all the mates in the solution. [This message has been edited by ctrlaltdel (edited 04-15-2002 07:56 PM).]
ctrlaltdel
Member of the Daedalians

 Posted: Wed Apr 17, 2002 9:14 am    Post subject: 14 comeon coyote, more chess puzzles?
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