Solution to the Christmas puzzle

This was the Christmas puzzle, which we posted on December 25 2000:

A game ends with the move  6.gxf8=N mate. How did it go?

The answers started coming in literally minutes after the problem was uploaded to our server - the first correct solution arrived just fifteen minutes after publication. And the number of correct solutions was extremely high. Below you will find a sample of the messages we received. Hopefully all solvers who sent in the correct solution are included (use Ctrl-F to find your name).

The winner of the special prize is Sujey Subramanian, a young master from Hong Kong, whose solution was one of the first to arrive. Sujey gets a copy of Deep Fritz which was personalised by FIDE world champion Vishy Anand ("To Sujey...") on the last day of the Wijk aan Zee tournament.

And here is the solution to the problem. Do keep visiting our puzzle section for new teasers and chess problems.

Letters

Ben Tilly: This took me about 20 minutes to find by hand with a board in hand. It is obvious that white has to spend the whole time marching a pawn with but one move to spare. It is also clear that black has to put the king on d7. Something has to go to e8, and clearly a knight will be easiest to maneuver there. I started assuming that said knight would be from g8, and focussed on how to block off all escapes for the king. After a few false starts I realized that the best way to do that was with the white rook. This left a lot of time for black to do maneuvers. I spent a lot of time thinking about solutions where white takes the bishop and then takes the rook on f8. The timing never quite worked. Then it hit me that I could just leave the knight on g8 (blocking the rook) and use the other knight. It took little time to figure out what the correct sequence of moves had to be for that knight, and given how short time was, not hard to figure out the entire game. For the record I saw this on slashdot. [Wrong solution given].

Asifur Rehman Qureshi: It is wrong puzzle. No solution.

Dennis Monokroussos: [Correct solution given] It took me about 40 minutes to do it--I realized pretty quickly that the king had to be on d7 and a knight on e8, but I had two mental blocks to overcome. The first was that I tried moving the g8 knight to e8, when of course I had the problem of figuring out how to get rid of both the Bf8 and the Rh8. The second problem was that I attempted ...d6 instead of d5, with the idea of putting white's queen on f3 or bishop on g2 to cover the diagonal. The realization that it had to be the b-knight came first, and I stared at the position with the pawn on g7, the black knights on g8 and e8, black pawn on d6 and king on d7, and thought about what white piece I'd like to have anywhere so that gxf8=N would be mate. First I thought of some line where Bh6xd2+ happens, followed by Qxd2 and Qd5, but that takes far too long, of course. But then a second look and I saw a rook on h6 would just about do it...if d5 gets played! And that was it.

Kenneth Jensen: [Correct solution given].

Albert Jiang: [Correct solution given]. It took me about 30 minutes. First I made sure the black King won't have time to make it to h7, so it has to be mated at d7. Then I started working on the scenarios... It seemed that black itself don't have time to make the smothered mate happen, so it needs some help from white. And indeed white has one "spare" move left, besides the pawn moves. Then I tried to figure out which pawn white should start from. The e, f, g, h pawns are more probable candidates. To make white's "spare" move useful, white should probably start with e pawn, or ... h pawn! Once I set my eyes on h pawn, everything else is easy. The natual "spare" move is Rh6, and therefore black's d pawn should be at d5 to stay out of the way... the last task was to find something to fill e8, and that was pretty easy too. Thank you for the puzzle! It was fun! Have a Merry Christmas and Happy New Year!!

A. Zeyliger: [Correct solution given].

James R. Quinn: [Correct solution given].

Sujey Subramanian: Heya! This puzzle was great! Being a junior tournament chess player I went straight to the board to take on the challenge. It took me about 10 minutes, and gave me alot of satisfaction when I solved it. The thoughts that came to my head were that 5 moves would be used to promote the pawn, which would probably be either the h pawn or d pawn. Knowing that the mate was at f8, black's moves had to be focused on boxing his own king and making sure that the f8 was unprotected at the final stage. A lot of my thought was on 1... d6, but when I realized the value of the rook, the entire puzzle became clear. [Correct solution given]. Even if I dont win, I will always remember this puzzle. Thank you.

D. Eppstein: [Correct solution given]. Five minutes with a chessboard. I first worked out possible paths for the white pawn, and discovered that by using the rook pawn I could bring up the rook to help. Then I found a sequence of black moves that would put the king on d7 and block its retreat back to e8. Don't include me in the Deep Fritz prize drawing, I don't have a PC.

David Bellows (him we remember!): Well this one certainly seemed easier than last years, so here's my reasoning and then the solution: First a quick count with your pawn reveals that it takes five moves to get the pawn promoted. This leaves you with only one other move to make to get a supporting piece out -- so it had better be a good one! My first thought was to move out the King Rook Pawn and let it capture its way over to G7, freeing up the Rook to come down to H6 or H5. I spent a lot of time on this. I quickly ran into a problem with the black queen being able to knock out the advanced pawn, so I had to find ways to get her out the way. This approach required moving several black pieces around and I kept ending up the the black king fairly far out and with plenty of room to get around in. So I switched up and began moving out the pawn at e2 in order to free up the white queen. The thinking of course was that given her greater attack mobility that she could plug up the holes left open from my previous attempt. The dynamics were slightly different, but I kept having the same problem with moving several black pieces and always leaving the king an escape. So then I decided to think "outside the box". Instead of making the pawn the check-mating piece I tried to find a way to bring the white rook to H7 with the king on *7 and by moving the pawn to F8, this would expose the King to the Rooks check and hopefully with the proper placement of the other black pieces the newly promoted pawn would fill up any escape routes for the King. I was sure that this was going to be the answer as it involved approaching the problem for a different angle than was apparently obvious. Unfortunately Black's rook at H8 was posing a pesky problem (preventing the white rook from checkmating). So then I spent some more time trying to get the black rook out of the way. Whew. Alas, to no avail. So then I began thinking that since you hadn't specified which black piece was to be captured by the advancing pawn that maybe it wasn't going to be Bishop (the obvious choice). So I tried "thinking outside the box" again. The only possible choice was the black queen in the bishop's place (F8). Unfortunately it took too many moves to get the queen over leaving me without many options to get the King pinned down in a checkmate. I quickly exhausted my options. So then I reset the board, decided to start over and eat lunch. While looking at the board with the rook at H6 I saw that if I could keep the King from retreating back to his starting square that I might be able to force a mate. I had seen this problem many times before and my solution had been to keep pushing the king further and further out while clogging up as many squares as possible. So I began wondering if there was any piece I could get to exchange places with the king while keeping everything else the same. I gave up and instead started moving the black knights around during the opening moves (instead of pawns, as had been my approach). Nothing was coming to me. And then in one of those lucky moments I saw the black Knight move: D7, F6, D8. I got very excited, Unfortunately I couldn't remeber why this was important. So I started doing this and quickly saw the solution (as related to above re: only exchanging places with the King)! In fact it almost played itself out (as opposed to last years puzzle which had a couple of different sticky situations to get through before achieving chackmate). The approach using the White queen was obviously a no go since I couldn't get her far enough down the board to force a mate on *6. I was happy that my first idea of using the H pawn in combination with the white Rook was the solution. So here it is: [correct solution given]. Final note. I don't know if anyone on Slashdot has posted the solution. I have been waiting all year for this puzzle and have consciously avoided looking at the comments while working on the solution. I was also glad that you chose another puzzle that was based on a mate during the opening moves -- I never have been able to get those puzzles that have mates deep into a game. Thanks for another enjoyable Christmas Chess Puzzle. P.S. In case you don't remember me, I was the one awared the prize last year and so I don't expect to be in the running for this year's prize. I just enjoy the challenge of the puzzle!

Jager Mcconnell: [Correct solution given]

Felix Müri: [Correct solution given]. Today is christmas. I needed about 3 hours to solve the problem. The following steps helped me: - White needs to do 5 pawn moves and one other move. The other piece can only be the queen or a rook - It is not possible to mate by freeing a line (Abzugsschach in german) - I looked about 1.5 hours for a solution with black king on e6 (after d6) and either queen or rook on the 5th line. But there are two problems: -- The queen must not be able to take the white night -- f6 should be occupied by an black piece. The real problem are not the white moves, but the black ones. Thank you four your puzzle (thats the kind of puzzle I love even more than the ususal white mates in 5 moves...)

John Chernoff: [Correct solution given]

Richie Lai: Sorry my chess notation is a little rusty so i'll do what i can.. Arg hit send too soon.. It was actually quite easy to solve.. Knowing it would take 5 moves to get the pawn to the gxf8 position, all I had to do was find out what position black had to be in to be put into mate. Also knowing that i had 1 move to spare, the only piece that had the reach to do anything useful was the king side bishop that the pawn opened up. Once all that was established, I just found the shortest way to put the king into a box. The problem only took about 20 mins to solve but it was definately fun.. I took a disliking to chess puzzles after the 8 queens program i had to write in college, but this was entertaining :) [Wrong solution given]. PS do you email back to let us know if we got it right? I'm more interested in knowing I didn't screw that up :)

Daniel Grenier: [Wrong solution given]. Time to solve it 10 minutes, well it was kinda easy, since any pawn will need 5 move to go to g8 then theres 1 move left for the white Qg4 was the only move that make sense then all the other move are simple to find.

Peter McKenzie: [Correct solution given].

Walter Waltz: I knew the king had to be moved to d7 for the knight to checkmate it, and it had to be trapped in by the rook; but how to go about doing it I was unsure. I then had a few solutions, many of which ended me up with game in 7. I then stumbled upon this: On the first move white moves pawn from h2 to h4. Black then moves pawn from d7 to d5. On the second move the white pawn advances to h5 and the black knight moves from b8 to d7. The white pawn advances again to h6, and the knight moves from d7 to f6 The white pawn takes the black pawn on g7 and black moves the king diagnally to d7. The rook then comes up to h6, and the knight moves to where the king was on e8. The white pawn takes f8 and promotes to a knight which ends the game with white being the victor.

Matthew Blakley: [Wrong solution given]. Took about an hour. Started by trying to set up the final position. I realized the pawn could be in place in 4 moves and another piece could come out and help. First looked with the bishop, briefly with the knight, and then with the queen. The queen on h5 maximized coverage in the correct area and a bit of work identified the black piece placement. It was then a matter of finding the combination of moves to realize the position.

Shawn: Hi, i belive i just completed the chess puzzle, unfortunatly im not too farmiliar with the notation of chess moves so ill try and fill out what chessmaster 5000 has left in the move logs. It took me about 5 minutes total, thats why i think i was doing something wrong. [Wrong solution given]

Ross Wolf: [Correct solution given] solution took about 20 minutes. Counting white's moves, white only gets 1 move, besides the pawn advances to have any effect, whats more, a checkmate by a knight at f8 only gives 4 possible squares where the king must be in order for that move to cause a mate. Once that was derived, it just took moving pieces around looking for a possible mate setup. Black was going to have to trap himself in, and the extra move alloted by white had to be either a rook or a bishop to assault a few squares, and the rook seemed easiest from the pawn which was moved by white.

Sarkis E.: [Correct solution given]. Took about 30 minutes messing around with a computer chessboard.

David Menestrina: [Correct solution given]. It took me about 20 minutes. The big part was realizing that it's not the g pawn that moves up. If it did, black would have to make some moves to help the pawn to g7. After I figured this out, I tried to move pieces to prevent the Queen from getting the knight. First I tried the g knight, but then realized that the g knight was important in preventing the rook from taking the white night. Then I tried the c bishop, but that took too many moves. Then I tried the b knight, and it worked! Either I have improved since last year (I never solved that problem), or this problem was much easier.

Tom Petrillo: I noticed last year many ppl sent you how they found the solution, this is my story (because it was a 3 hour epic to find the solution, I must share...):First let me preface how I first thought I would attack the problem. I figured that since it takes 5 moves to promote, I must move a pawn that opens another piece which will block the black queen or remove some valuable square. At first I thought I might be pinning the queen to the king some how, but all attempts failed, I was trying to work something out from this line which mates in 7: 1. d4 e5 2. dxe5 f6 3. exf6 Kf7 4. Qxd7+ Kg6 5. fxg7 h6 6. Qe7 Kh7 7. gxf8=N# (as pasted from chess base light, as w ill most of the rest of the notation for I am bad at doing it) But to no avail, it was impossible. BUT, what I did with the queen was very eye opening. I tried to do it with a rook on the h column (file??). The A column was too far away, period (so it's rook was useless. So this time, I wasn't going to use all my moves for the king and instead decided to put the knight where the king is to block the queen. It had to be the knight on c8 since the other knight is in use blocking a rook. Well, this li ne was my immeadeate idea: 1. h4 Nc6 2. h5 d6 3. h6 Ne5 4. hxg7 Kd7 5. Rh6 Nc6 6. gxf8=N+, where I block the escape instead of the king, and it looked like I was moving in the right direction. Well, it now seemed clear as to what I needed the knight for, I saw a quick 3 move combo to get the knight in as a blocker with 1..Nd7 2..Nf6 3..Ne8 And this was the key... an easy combo followed: 1. h4 d5 (I originally had d6 which fails, but when I got to the end, I could not believe my eyes!!!) 2. h5 Nd7 3. h6 Ndf6 4. hxg7 Kd7 5. Rh6 Ne8 6. gxf8=N# (as pasted from chessbase with much triumph). wow.... It took me a while... good puzzle, thanx for the fun, I think i'll try my hands at last years puzzle...

Derrick Chung: [Correct solution given]. It took me about half an hour working it out over the chessboard. I basically looked for spots where the king must be in order to be checkmated this way as well as ensuring that nothing could attack the new knight. Also, White was only allowed one non-Knight move which had to restrict the king's movement. I put it all together to give me the answer above.

Lev Makhlis: [Wrong solution given] Took me less than a minute -- very much unlike the last year's one. :) Reasoning: it takes a pawn 5 moves to get from 2 to 8, so white only has one non-pawn move. The most obvious use for that one move would be to ptotect the promoting pawn. So - Qf3, and f6 just happens to clear the way.

Calrathan: [Correct solution given]

Shawn Bender: [Wrong solution given]. The pawn becomes a knight and the black king is checkmated. It took me about half an hour. I knew for the white side the pawn required 5 of the moves and the rest was just a matter of getting the king trapped.

Paul Walker: [Wrong solution given]. It took about 5 minutes. Whites moves are pretty straightforward...you know that you would want a diagonal take in either direction to move back to file 6. Knowing that black king would have to be in d7, it's easy enough to see that a bishop move to g2 could be used to prevent the king from moving to b6. The two remaining black moves are used to move the knight to the original king position at d8. No chessboard was used except the one on the expanded instructions page.

Matt: Try switching the king and queen with each other on each side of the board. (Qd1->e1,Ke1->d1,Qd8->e8,Ke8->d8) I figured out that by doing so, the solution to this same problem is similar, but requires no arbitrary moves. Here is the solution: [Wrong solution given]

Roman M. Parparov: 1.h4 d5 (Janowsky-Consultants, somewhere circa 1900), 2.h5 - white is determined 2....Nd7 - black wants to continue development 3.h6 - excelsior! 3....Ndf6 - ignoring the pawn and continuing to improve the piece's positions 4.hxg7 Kd7 - black's king is getting scared 5.Rh6!! - let's give the pawn our support. 5....Ne8 - finishing the packing 6.gxf8N MATE Took me about 15 minutes, before I was getting afraid about another workday going to hell. Seems, I am getting the spirit of these tasks.

Christopher Clark: [Correct solution given] I just submitted the answer for the problem and I guess that I am supposed to make some comments and such about the problem. It took about 35 minutes to solve and it was all a matter of seeing the possible mating positons that are in or near the back ranks (7 and 8.) It is also necessary to surround the king in the minimal ammount of moves. The king, which has only 2 realistic positions, was where all the trouble was. But after contemplating the introduction of the knight or the rook, the solution presented itself. The other problem that I had was to figure out how to keep the black rook and the queen from attacking f8, the promoting square. That is where the nifty knight move came into play. Well, thanks for the chess problem, it was fun, Christopher Clark

Stuart Lamble: [Wrong solution given]. How long: five minutes. How did I solve it: First, it was obvious that the king had to be in one of four places: d7, e6, g6 or h7. h7 can be eliminated, since g7 must be an empty square when the mate occurs; the same applies to g6. e6 can be eliminated, as it would require at least five moves (five squares) simply to fill the surrounding squares, without taking into consideration the king's movement. Ergo, the king must be placed on d7 for the mate to succeed. Six moves is exactly the number required for a pawn to move, one square at a time, from the base to the 8th rank. This makes White's moves easy. (NB: an equivalent mate can be obtained by using the h pawn instead of the f pawn.) That leaves Black to examine. The first two moves put the king into position. Now we need to fill c6 and e8. c6 can be filled by moving the knight on b8 -- that leaves e8 to be filed. (I originally worried about e6, then realised that the mate didn't have to be a smothered mate, and that White's knight would cover that square nicely.) I have two moves to do the job. Bingo -- knight from g8 will do the job. False paths along the way: I originally had the knight taking the pawn on f6 (after it moves there one square at a time), not realising that the two pieces needed to occupy that square simultaneously. Solved by making the f pawn proceed two squares instead of one, and having a filler move by White at move 5. There were other similar mistakes, involving the assumption that e6 also needed to be filled. Hey, give me a break -- it has been some years since I last played chess! :-)

Sujey: Hey, Sujey again. This is not a solution or anything, I'm the guy who solved it before. I was wondering what your real name is/ and am asking for permission to use this puzzle/and or last year's one in my weekly chess column in the newspaper. Yeah, I am 16 and write a chess column, but then again, there are 15 year old GMs (Bu). Is last year's puzzle story based on your experience? If so, wow!. I am talking to a guy who rides in cars and is friends with world champions.

Léon Buchholtz: [Correct solution given]. It took me about an half hour. I made the mistake that i didnt see how to play that black cant escape to c6. My first move of black was every time d6 instead of d5. I saw directly that it must be the h-pawn who must run to activate the rock who helps to mate the king. (nice problem)

Erling Kopperdal: [Correct solution given]

Frank Gifford: [Wrong solution given]. Details: Starting with a white Knight at g8, it takes five moves for a pawn to reach that sqaure via (e4 or g4) f5, f6, f7 and then g8. So there is only one extra move for white. Black needs to move f7-f5 on his first move. As part of this, the only places for black to be in check from a knight at g8 are on e7, f6 and h6. The first two require too many other moves from black to lock the position up while h6 looked promissing. The white queen can come out and block in the king. Trying the order of the moves gives black one extra move and moving black's c pawn gives the final position a little polish! Total thinking time: about three minutes.

Jay Wherley: [Correct solution given]

Thomas Kircher: [Correct solution given] Having spent the day in a christmas haze, I unfortunately posted an incorrect sequence earlier. I decided to use xboard to check my positions, to avoid any further embarassments. ;) This took me about an hour. I started by looking at the squares which would be under attack by the knight in its final position. I tried assembling various configurations where the king occupied those spaces, and only had an opening to the other threatened square. It didn't seem likely that g6 or h7 would work - I tried castling, and moving the queen to attack g7, but those took too many moves. I convinced myself that the rook was the critical piece, since it was easy to open up; at that point, it was a matter of minutes before I found the above sequence of moves.

Teun van der Zijden: [Correct solution given]. This was great to try and looked very difficult at first, but all in all it didn't take me more than five minutes to find the solution. The key is to realise that in this situation the rook is far more efficient than the queen, because the rook can be brought into play by a single move and the queen needs two; therefore one must use the h-pawn instead of the f-pawn. And from there on it's easy to find the solution. still I had a great time trying: thanx!

Woody: OK, I'm not great at writing chess notation (another slashdot reader) but I'll give it a shot... H2->H4 D7->D5 H4->H5 B8->D7 H5->H6 D7->F6 H6x G7 E8->D7 H1->H6 F6->E8 G7x F8 N check mate

Ed Severn: [Correct solution given]

Leo Mano: [Correct solution given] After 40min. A different "construct the game" problem: The last move was showed in the question instead of the diagram with the final position. Very nice.

Roman Sulzhyk: [Correct solution given] Yes, hello. I'm an average player - 1900-2000. Solved in about 20 minutes. Realized pretty soon that g knight should stay put to block the rook. c bishop could not block the e8 in time, so had to use the knight. The final touch was to make d5 the first move - took a bit to figure out. Thanks!

Sowmith: [Correct solution given]

Tonni Mogensen: [Correct solution given]

Gurbuz Aslan: [Correct solution given] White has 5 pawn moves and an extra (probably non-pawn) move. First question is: What is the first move? Answer: 1.f4 or 1.h4. Second question is: What is the White's extra move? If first move is 1.h4 (this move is better than 1.f4), White's non-pawn move must be a Rook move. Rh6(!), Rh7 or Rh8?

Bruno Barberi Gnecco: [Correct solution given] This year I made it. ;) Here's a quick history of how I found it: first I did an analysis, to find what pieces were most suitable for the task. I found that I probably would have to move (or at least use) the white queen, queen's bishop or rook. And three pawns were interesting: d, e, h. The end of game: there were four possible positions. At first I tried h7, which quickly showed impossible, since it took 5 moves just to put the king in the right place, and so I couldn't prevent the queen from capturing the promoted pawn. I did several attempts, sometimes carefully following a method, sometimes just following an insight. I won't bother you with all I did (there are nine "close" solutions in the paper in front of me, and I probably found another 4 or so). They all missed a square, or two, or the knight was captured by queen or rook. I find worthwhile to mention one path: for some time I thought that the queen should be captured by the pawn. It gave some close ones, but again and again nothing. I gave up for a while, then, and finished the book I was reading (William Beckford's "Vathek", for the registers:). I was kind of sleepy, and decided to lie down. Of course, I kept thinking of the puzzle, and the dark helped me to carefully examine the possibilities. Trying to figure out one more time which one of the possible 4 positions that the king should end, I was always inclined to e6. It was easy to get there and to get rid of the queen, which made me lose a lot of time. Finally, trying to figure out how I could use the g8 knight and still prevent the rook from capturing the pawn, it crossed my mind that if I could put the other knight in e8, it would solve my problems, and that's how I found the solution. I read the post in slashdot at noon, but forgot about it until about 4 or 5 o'clock (local time, Sao Paulo, Brazil). The solution struck me at midnight. I probably worked a little less than 4 hours in the problem. Thanks for the pleasant evening I had. And post it more often at Slashdot. I don't play chess so often anymore, but I still enjoy it.

John Phillips: it cannot be done it takes the pawn five moves to reach the top.

Warren L. DeLano: [Wrong solution given]. Total time spent: about 1 hour; solved by and trial and error and deductive reasoning. Used Fritz 5, but only as a chess board with memory.

Iceman: [Correct solution given].

Vincent Mccorry: [Correct solution given]

Michael Scheidl: Sehr schwer. Zuerst habe ich alte CSS-Ausgaben bis zum Jahr 1993 zurück durchgeblättert, weil mir die Aufgabe bekannt vorkommt. Gefunden habe ich nichts. Mein Angebot: 1.h4 e6 2.h5 Qg5 3.h6 f6 4.hxg7 Kf7 5.Rxh7 Kg6 6.gxf8N+ Naja... ich habe auch Lösungen gefunden, allerdings in 7 statt in 6 Zügen (leider nicht gespeichert). Ich glaube, e- oder d-Bauer kommen auch in Frage, aber ich hab's nicht hingekriegt. Die Lösung muß an ein Wunder grenzen - wie üblich.

Bernd Rieger: [Correct solution given] 15 minutes with 2 persons blocking Rook and Queen from capturing Knigth, because King must move -> other Knight must move to King's position

Thorsteinn Asmundsson: [Correct solution given]

Edward Khachatryan: [Correct solution given] It took me about 30 minutes to solve it.

Troy Sartain: This took me over an hour (I'm not a grandmaster!) :-) Had to realize 3 things: - the promotion caused the check (directly or not), - the new knight needed to be free from capture from either black's queen or rook, - and black's king needed to be trapped (by white's rook in this case.) The last two comprised the hard part; how to plug all the holes for the king's movement while not threatening f8.

Emily Warlick: [Correct solution given]

Gerardo Malazdrewicz: [Correct solution given]

Eugene Lim: Hi Frederic, Taking time off from doing some annoyingly tedious physics problem (I am a grad student), I found the solution as follows: [Correct solution given]. It took me about 3 hours over a couple of days to figure it out. I think this year's puzzle is relatively easy, though I was misled this time by both (1) d4 (bringing the queen out early to cover more squares) (1) e4, aiming for mates at g6. Once I saw that I can get the b8 Knight to go to e8 in 3 moves, I knew the answer has to be mate at d7. Method: Analyzing the problem is relatively straight forward : Black has 5 moves to set itself up for suicide, and White has 1 "non-pawn" move (i.e. piece move) to help Black along. Mate has to be either in g6 e6, or d7 (h7 needs too many moves to set up and the black Q has no time to get out of covering f8). e6 is easily discounted since the squares at e5 and f5 cannot be covered with one White move. Mate at g6 with White rook at h7 and black pieces suffocating the BK blocking g5,f6 and f5 needs one Black move too many as a simple count can show (one does not even need to figure out which piece to use). That leaves d7, which means I need to prevent the black queen from covering f8. That's when I started looking for a piece to go to e8 and the QN is the only piece possible. The 6th rank can be conveniently covered by Rh6, the one White non -pawn move allowed. Other tricks I used to quickly get rid of lines are ignoring "non-forcing moves", i.e. attempts with move order that can be swapped (usually a sign of error). Now that I have solved it, I have no more excuse NOT to do tedious physics problems :(. Merry Xmas and Happy New Year!

Pierre Bourget: [Correct solution given]. Took me a couple of days to solve it.The idea of rook on h6 to cut the king is great. Very good puzzle. I have compose the following but i don't know if it is already known. Here it goes: In the starting position, white to move first, and black to give checkmate on his fifth (5th) move by promoting a pawn to a bishop. Not a force sequence, but cooperation by both sides. Solution available by eMail.

Paul Vianna: [Correct solution given]. I spent around 30-40 minutes, then had dinner. After dinner, I found it in a couple of minutes (a break often helps!)

Jan Jongerden: [Correct solution given]. This took my roommate and me about 2 hours, getting more and more frustrated about the impossibility to achieve the mate, however after a couple of beers we somehow saw the light and got the big picture "Im bezeichniss zeigt sich den Meister" (in confinement the master shows) some german once said, and I agree. [Actually it is "In der Beschränkung...", Jan].

Cem Gomel: [Correct solution given]. it took me about an hour to figure it out. my reasoning was: first see if it could be mate by a disovered attack. when i figured out that it couldn't be i looked at all possible places the king could be at at the time of mate. then i tried to put black into a position of no escape without moving any white pieces. (note that white can only make one non-pawn move.) i guessed that Kd7 was the best spot to mate. i also tried to figure out how to make the f8 square not protected by black in 5 moves. the solution kinda came out of all these constraints.

Luc St-Louis: [Correct solution given]. Oops, using S for Knight there -- old problemist convention ;-) The puzzle is much simpler (it took me 15 minutes) than last year's (many hours!). I got stuck a while trying to mate with the g pawn and a B on g2. That required a BP move on either the f or h column for the W pawn to capture, but left B with only two moves to block e8. It could be done with Sg8-f6-e8, but that allowed the BR to capture our promoted S. Contrary to last year's puzzle, the order of no moves can be changed, which is a plus. I am curious to know who the composer of this puzzle is. Could you mention it on the puzzle page perhaps? I suspect not many problems of this type have been composed. I wonder in which year you'll run out :-) If you're into chess problems, you probably know about `proof games' problems. If you're not and are interested, drop me a line and I'll email you a couple of recent prizewinners from The Problemist. Thanks for maintaining the page. Luc "not-a-chess-player-but-likes-chess-problems" St-Louis

Ingram H. Braun: [Correct solution given]

Pat Porter: Aaaah hockey. The great Canadian inspiration. I took a break from this puzzle to watch Canada v. Finland at the World Juniors when the solution hit me (right along the boards, as it were.) [Correct solution given]. Incidentally, the score in the hockey game was also 1-0 for white (Canada) when it hit me.

Ken Payson: [Correct solution given]

Jose Vilarnovo Caamaño: [Correct solution given]

Sivasankar Chander: [Correct solution given]

Adrian Tymes: [Correct solution given]

Daniele Ruggieri [Correct solution given]: I found the solution in a couple of hours. 1. The pawn moves are 5, so there is a piece that collaborate in the mate. This piece can’t be a knight. 2. The black king have to be in d7, e6 or g6. I consider first the more natural d7. 3. A black piece must interpose in e8, and this piece is the QKn, that can reach e8 in three moves. 4. The first guess is that the white queen is involved, but I can’t find a mate position trying e4 f5, exf Dh5 and so on. 5. I finally find a mate position with the black king in d7, the black QP in d6, the black QKn in e8 and the white KB in g2, but in this way the g pawn can’t reach f8 6. Finally the right idea. The right piece is the KR, and the murderer is the h pawn. The black QP have to go to d5.

Chad Ritchie: [Wrong solution given] Checkmate. It took about 20 minutes. I sat at my board and found where the King would have to be mated. Realized I could only move one additional piece aside from a pawn. Once I figured out the Queen's spot it was almost over. The last peice was just timing the Knight move correctly. Which I confess was the part that took me the longest :) This was a great lesson for me, I only started playing chess last year and at 24years old no less. I have played everyday since I started and I am constantly amazed by how much I have yet to learn.

Chad Ritchie: Ooops hehehe I got so carried away with the position I forgot about the rook. hehehe hahahaha Oh someone hit me. OK, back to the drawing board.....

Keith Lee: [Correct solution given]. It took about 15 minutes to solve. First, the Black King must end up on a square attacked by N on f8: the closest to its original square is d7. Also, the quickest way to get a White P to g7 is via the f or h files. The h Pawn seems more likely, since it allows use of the White Rook. The Black moves should contrive to block escape squares from the Black King, and must also prevent the f8 square being attacked by Black Queen or Black h8 Rook. With the above points in mind, it is quite quick to find the correct move sequence.

Juan Carlos Sanz: [Correct solution given]

Chin Lee: Solving the puzzle took me around half an hour, while eating dinner. I basically played around with the pieces on a board, trying to put the Black King where it had no escape squares. [Correct solution given]

ShenYong: [Correct solution given]

Gregorio Aragon: [Correct solution given] I read your puzzle last December 28 at 11:30 pm and tried to solve it up to Dec 29, 2:00 am and failed. I resumed solving the problem at Dec 29, 10:00am-10:30am and failed again. While lying in my bed, Dec 29, 12:30 pm the solution just crossed my mind and I jump out of bed quickly and checked my solution. I got it!!!. Here's how I went about it: I set up white's knight at f8 with a check. There are 4 squares where black king should be to be under check (d7, e6, g6, h7). I disregarded g6 and h7 squares because the g7 square will be empty after white makes 6. gxf8=N move and black king can use this square to escape. I also disregarded e6 because of too many flight squares. I concentrated my mate at d7. Since the puzzle requires only six moves, and 5 moves of which will be use used by the pawn, therefore I can only use an extra move for any piece. Also, the piece on f8 must be unsupported to execute mate on the sixth move. The black queen has to leave d8/e8 or any black piece (bishop or knight) must move e8 to break the queen from supporting f8 square. The move 2. ... d5! is the key to the solution since the rook move 5. Rh6 cuts the c6 square where black king will escape. Since last night I'm always trying the following set up to deny the c6 flight square. 1. ... d6 2. ... Kd7 3. ... Nc6

Allan Haley: [Wrong solution given]

Esteban Montot: [Wrong solution given]. I study a lot this, but the king always has got free the square f6, so I use another play. I in Argentina and little people play chess, so I like to play by Internet.I have got only the program Fritz 5 for play. I like all related with chess.

Dario Uzunovic: [Correct solution given].

Marco Bergsma: The solution took me about 15 minutes. I was thinking it over without the board and it seemed to me that the King should be on d7 and a piece must be on e8 while a white heavy piece must be on the 6th rank! I first tried 1.h4 d5 2.h5 Bd7 but then the king can't come to d7 so when I tried the Knight it all was clear! So here's my solution; hope it's correct as i didn't bother reading the explenation [Correct solution given].

Clauder Montot: [Correct solution given]

Caroline Lee: [Correct solution given]. I solved it in 40 minutes. I tried moves out and then tried to modify them to eliminate problems preventing checkmate, e.g. when Black could move the King or capture the Knight.

Laurent Tinture: [Correct solution given]. Time taken : a quater an hour with my father Bernard waiting new millenium... Method: Find the mating position and the move order next; the path of the b knight and the move Rh6! were pleasant to find. The trap is that you begin the black sequence with d6 and you reverse to d5 when you feel the move Rh6. A fine helpmate with a unique sequence order... Happy new year and millenium.

P. Wiereyn: [Correct solution given]. It took me about 2 to 3 minutes. First I looked where the black king could be mated and square d7 seemed the most obvious one to me. From here it is rather easy.

Umesh Nair: [Correct solution given]. It is easy to find that W needs 4 moves to get a pawn to g7, that leaves W one non-pawn move. Now BK should be at d7, e6, g6 or h7 (other possibility is BK is on g8, and 6.gxf8=N+ is a discovered check, but for that B has too little number of moves.) The ideal square is d7, so that only c6, d6 and e8 need to be covered. e8 need to be covered with a N or B so that BQ doesn't control f8. So the initial vestion is: 1. h4 (or f4) d6 2.h5 Nc6 3.h6 Nf6 4.hxg7 Kd7 5.any Ne8 6.gxf8=N, but the BR at h8 now controls f8! There are not enough moves to move this piece. So, what remaining is, use the other N. 1.h4 (or f4) d6 2.h5 Nd7 3.h6 Ndf6 4.hxg7 Kd7 5.Bg2??? Ne8 6.gxf8=N#. Now we need to cover c6 on the 5th move. Initially, it appeared to me that only a B or Q can cover that. Here comes the main problem. For that we need to move the 'e' pawn or 'g' pawn. e-pawn is too far to reach g7, and so is 'g' pawn!; BP at g7 blocks it! (Too bad pawns cannot capture straight!). I almost gave up here, but suddenly found that The WRh1 can be used to cover c6. But the d6 pawn will block it. Oh, no problem, we can move it to d5, and WR covers both squares. So, the solution is 1.h4 d5 2.h5 Nd7 3.h6 Ndf6 4.hxg7 Kd7 5.Rh6 Ne8 6.gxf8=N# !! Very good problem ! Thanks.

Ben Lynn: [Correct solution given]. The first day I couldn't do it, but I did solve last year's puzzle, after reading a big hint. (I had completely forgotten about it after giving up early last year.) I returned to it during spare moments, and now I've finally stumbled across the solution. I had tried to win with discovered check (advance the h-pawn and do Rxh7, while Black tries to clear the space in between) but there wasn't enough time. I also explored advancing the d-pawn and e-pawn, so that the queen could come out and help, but there always seemed to be at least one square left out. I also briefly considered moving the king to h7 (almost succeeds), and castling (and then moving to h7) which seemed hopeless. The h-pawn still looked the most promising. It took me a long time to work out how to fill e8. I had tried using the knight at g8 (which means the rook at h8 has to move down somehow), but 3 moves weren't enough (the other two moves of course are spent on the king and pawn moves). Then I realised the other knight could get to the right square in 3 moves.

Gary Baydo: [Correct solution given]. I spent about 3 hours solving this. Most of the time I simply played all of one colors moves together in order to find positions that held promise. Thanks for a neat puzzle.

Stuart LaMonte: [Correct solution given]. Originally I had tried the KRP, but then I convinced myself that both the white Q and QB had to cut off squares from the black K. After trying e.p. and pawns all the way to the Qp and trying to get rid of the black Q on f6, I finally realized the QN could cut off the black Q in just 3 moves and the rest came quickly. Total time: about two hours, 12:10 pm to 2:10 pm MST, Jan. 1, 2001.

Felipe Franciosi: [Correct solution given]

Roy Eassa: [Correct solution given]. It took me HOURS! So many lines were SO close. Several times I had the idea of using the b8 knight to plug holes on the kingside, but couldn't find the right variation ... until now!

Roy Eassa: [Correct solution given]. It took me HOURS! So many lines were SO close. Several times I had the idea of using the b8 knight to plug holes on the kingside, but couldn't find the right variation ... until now!

Meik Hoeller: [Correct solution given]

Geoff Saw: [Correct solution given]. I realised that White needed to use 5 moves to get a pawn to f8, and therefore only had one "free" move to set up a mating net. Rh6 presented itself as the only reasonable plan. After that, finding a solution was not too difficult.

Bart Meulemans: [Correct solution given]

Miguel Artigas: [Correct solution given]. I thougt about the problem during several days, and the total thinking time would be about three hours. After trying to solve it essaing some moves at random I decided to begin from the end and try to figure what would be the mate position. I reached the conclusion that there had to be a knight in e8 between the black queen and the white knight. Then I figured out that the black king had to be in d7. At that moment I sensed that I was in the right way but for me it was very dificult to decide which white pawn was to promote, since I found Ra6! that I think is the nicest and most hard to find move of the solution.

Reinhard Grünwald: [Wrong solution given]. Solved in about 2 Min with out a board. I figured that the bK needed to be at the edge in order to minimise its space, so it had to be h7. Exept pawn moves you have one free white move. Because gf7: leaves g7 unoccupied, this move had to cover g7, so it had to be Qg4. That meant the e-pawn had to run. That was it.

Kristian Chenu: [Correct solution given]. I got the dope moves, man!

Greg Ingram: [Correct solution given]. I'd estimate that it took me 2-4 hours over a couple of different sessions. Given that it takes five of white's six moves to make the required ending move, I'd figured the one last move would use the King's Rook since it would be able to cover a lot of space. Black has to use all of his moves to lock himself up. Once I started playing with the Queen's Rook, the solution came quickly.

David Paul: [Correct solution given]. What a fun puzzle! I was able to think it through logically with some effort. I wish I could say the same for the NxR mate puzzle that I'm still wasting my life away on. :)

Roberto Cid Coutinho: [Correct solution given]

Jari Kylmälä: [Correct solution given]. Nice one! :) It took about 15 minutes to solve the problem. First I noticed that 5 white moves are required for pawn to march and mate with gxf8=N so white has one extra move. It was clear from the beginning that the black king must be on d7 when it's checkmated because other scenarios used too much moves. So I started to think what might be the useful extra white move. To get pawn at g7 without black assistance white has to start with f- or h-pawn. F-pawn didn't look good because it didn't give other white pieces more space to move. But h-pawn looked interesting because it freed the h-rank for rook h1. The most obvious square for the rook was h6. There it was in great place because it threatened three escape-squares for the black king (at this moment I changed the first black move from d6 to d5 because it blocked the line and gave black king an esape square at c6). The next task was to fill e8 with black piece to prevent queen to control f8. Ng8 was no use because it already blocked the rook. To get bishop c8 there was too slow so the only chance was knight on b8. Three moves left for black and the knight's march just needed three so the puzzle was solved. This puzzle was quite easy after all because the line and even the order of moves is fixed.. wrong variations get cut off quickly.

Frank Mayer: [Correct solution given]

Andrej Lippai: [Correct solution given]

Joachim Heuser: [Correct solution given]. As always, after 4 desperate hours, the solution looks quite easy. Nice puzzle!

Marcio Schmidt de Azambuja: Hi from Brasil! Congratulations! Nice puzzle. It took me about 3 hours during 2 days to get the solution. I studied almost every possible variation, but the one that did work was the first one that I tried. Of course I missed something at the first time (d5). [Correct solution given].

Eduard Nemeth: My answer Frederic: [Correct solution given].

Roman Korba: [Correct solution given]. I solved it in about 1 hour.

Alan Gair: [Correct solution given]. I enjoyed this. It took me about an hour to do. I should like to know who the composer is and if this is the first publication.

Rakesh Rai: [Correct solution given]. It took me around four hours of effort spread over three days. The idea of moving the black knight on b8 was always there at the back of mind but I was ignoring it all the time (and considering moves by the other black knight, moving the h8 rook, moving the black queen etc.) White has 6 moves in all. White, of course, needs five moves for a pawn to reach to f8. So, he has one extra move (apart from the f8 pawn) to make. Black has 5 moves in which to set up the king. The Black king can be positioned at d7 or e6 or g6 or h7 (exhaustive). Moving the king to d7 takes 2 moves (one pawn and one king), e6 takes 3 moves (one pawn and two king), g6 takes 3 moves (one pawn and two king) and to h7 takes 5 moves). I tried different combinations but could not reach a mate on the 6th move. Always short by a move or two. For White's sixth move also, I considered different options like Rxh7; g4; e4, d4 etc. but these did not help. I agree when you say it was an astonishingly simple task. Just six moves...

Marko 'Joker' Djuric: [Correct solution given]. Hi. I'm a physics student from Belgrade, Yugoslavia. I first saw your puzzle last night and gotten to work on it. I almost had the solution very qucikly, I thought I had it with 1.h4 d6 2.h5 Kd7 3.h6 Nc6 4.hxg7 Nf6 5.Rh6 Ne8 6.gxf8=N+ but then I saw that the rook can eat it. I thought of moving the d pawn out 2 squares and saving a move for the black right away after that. I tried of getting the b knight onto e8 instead of the g night because then both the rook and the queen won't be able to take the night and that's when I made the huge,terrible and stupid error and oversight when I quickly glanced at the board and got the conclusion that the b knight can't get to the e8 square in less than 5 moves! I then tried a lot of different sol utions, I knew that the knight must be piece that gives the final check because if it was some sort of mask on the 7th rank it would take to many moves to set it up. Also since it takes white 5 moves to promote I knew that white had just one move that's not a pawn move. After some time I stopped working at the problem and had a go at your last year's Christmas puzzle, which up till now I still haven't solved. Some time after that I went to bed since I had to wake up early this morning. I wasn't too sleepy so I was trying to solve both probelms in my head. I tried out a lot of different combinations, started with different pawns (for a while I tried with the d pawn because it gets both the white's queen and bishop in the game) but I couldn't get the solution. I had a few mates in 7, I was pretty happy with 1.g4 d6 2.g5 h6 3.gxh6 Kd7 4.hxg7 Nf6 5. Bg2 Ne8 6.Nc3 Rh7 7.gxf8=N#. After some time I got back to the idea of keeping the knight between the rook and f8 and getting another piece between the queen and f8. You couldn't move the queen, that would allow an extra place for the king to go. I thought again of moving the b knight to e8. I thought since it starts from a dark square and must land on a light square so it must be in either 3 or 5 moves. I thought let's try to get it there in 3 moves and worked it out in a few seconds. I tried the combination in my head it worked, I got up and tried it on a chessboard, it worked so I went back to bed.

Paul Dunne: Well I'm doubtless far too late, but: [Correct solution given].

Georgi Benev: Hi. The solution to the problem i found fairly simple :). After all, the white pieces' positions are almost clear from the beginning, and i only had to figure the way the black pieces should move. I can say it took me only about 30 minutes to find the solution. If there are any mistakes in my notation below, please attribute them to my poor knowledge of chess terms in English. I've used K for king, R for rook, N for knight and no letter for the pawns: [Correct solution given].

Jukka Korvela: [Correct solution given]. It was difficult. It took me about 6 hours experimenting with pieces and 3 hours thinking and sleeping and nerves in 4 days. First I tried with e-pawn and conclusion was that it was not possible. Then I started to think which piece eliminates square-e8 and black queen from taking white horse on square-f8. That was succesful.

Martin Bauer: [Correct solution given]

Toivo Saarenpää: [Correct solution given]

Spiros Chrissikopoulos: Hello and happy new year.I am from Athens,Greece. I read about the problem yesterday.Very difficult one!:) The main difficulty for me was how on earth will both black rook and queen be stopped from capturing the knight. I take as granted that in the final position the black king will be on d7 since he will have to many escape squares from e6 and g6 and has no time to reach h7. So black queen must stay on her initial position( so that d8 is unavailable for the king. So the g8 knight must come to e8 and the h8 rook must leave from its initial position. The best way i found to do all these needed one more move for black. Which means that my solution ends with 7.gxf8=N# So I am posting it in the hope that 6.gxf8=N# was a typing mistake :) 1.g4 h5 2.g5 Rh6 3.gxh6 d6 4.hxg7 Nf6 5.Bg2 Kd7 6.Bf3 Ne8 7.gxf8=N#.

Rusdi M. Ali: [Correct solution given]. First, We tried to find mating position and a few logical information behind the puzzle, for example: 1. The Black King must be mated on h7, g6, e6, or d7 square. 2. Five moves of white move is a pawn move, only one move by other pieces. Rock or Queen. 3. The black queen must move or we must put other black pieces between the promote pawn and the queen so, there is no direct contact bettwen those two pieces. 4. We can not move the g8Night since there will be direct contact between h8Rock and the promoted pawn. If we move the h8Rock, it would take a lot of moves to settle the mate. And so on. After gathering logical information about the task, we began to find mating position beginning with the Black King on h7 square and using all possible pieces to create mating position. 5. First position, The Black King on h7 Square : This is imposible, The Black King need 5 move to be there, and the Queen still in its square, There will be direct contact between the queen and the promote pawn. If we move out the queen, it would take 7 move for Black king to be on h7 Square. 6. The Black king on g6 square : There will be a lot of hole arround the Black King and there is no logical mating position. 7. The Black King on e6 square : There is no logical mating position found, and no one of white pieces can keep all the hole including the queen, so it was imposible can be mated in the square. 8. The last option is The King on d7 square : this is the only chance since the others is imposible. We can not move the d8Queen, because we will need more than five moves and create hole for black king. So we must put a pieces between the queen and the promoted pawn. The choice is c8Bishop or b8Night. Moving c8Bishop will Create a hole. So the answer is moving b8Night to e8, and put the h1Rock on h6 square to keep a6 - h6 square. But those are not as simple as what explained above, specially after a hudred of trial and combination. After the mating position found, we then tried to trace back the shortest way from starting position to arrived in that mating position. After five days and small team, we found the solution. I can not stop thinking the puzzle for the whole five days before the solution found. Well, when are you going to send me the Deep Fritz. Thanks for Chessbase and all of you.

Márcio Tosta Gonçalves: [Correct solution given]

Jari Mannermaa: [Correct solution given]

Jesse and Joel: [Correct solution given]

Ralf Krätschmer: [Correct solution given]

Romain Schumacher: [Correct solution given]. It took me about an hour, and needed a rather unusual approach as one always has to find the worst move for black. It was a kind of trial-and-error.

Themis Argirakopoulos: I am not able to solve the problem. I need one more move... 1.h4 f6 2.h5 e5 3.h6 d6 4.hxg7 Ke7 5.Rxh7 Ke6 6.e4 Qd7 7.gxf8N# Or 1.h4 d6 2.h5 Kd7 3.h6 Ng6 4.hxg7 Ne8 5.Rxh7 Rxh7 6.a3 Nc6 7.gxf8N# I think that the black king have to be at d7 or e6 or g6 or g7. The moves are not enough for another piece to deliver mate (eg If I use my king's rook at h7, black has to play the moves : f6,e6,d6,Kd7 and Nc6 or c6 but the square e8 is free for the black king) I would like to spend more time on the problem but I am going to miss my exams in Complex Analysis... Are you going to reveal the solution in this page?

Jartsa: [Correct solution given]

Jari P. Perälä: [Correct solution given]

Benfurobot 1.0: [Correct solution given]

Husna: [Correct solution given]. First - find mating position and then find the methode how to achive the position it was not so dificult since there is only one mating position found where black need five moves, Other mating postion black needs more than five moves. we analize one by one the position It took ten days to solve the puzzle.

Van der Stappen Michel: [Correct solution given]

K. Narkunan: It took around an hour to come up with this answer, but I am still not sure this is correct as in the final position QxN can avoid the mate. In any case, I am enjoying working on it and I am going to continue until I have the answer. Dreaming to have a copy of Fritz. [Wrong solution given]

Roland Pfister: [Correct solution given]

Marc Boulé: The mate sequence is as follows: [Correct solution given]. If last year's Christmas puzzle required a whole computer lab at out university (20 Pentiums) during a weekend, this year's puzzle is more of the type Vin Nouveau: fruity, light, without pretension, nothing to upset the connoisseur; a single Pentium 700 MHz working during 8 hours was sufficient to determine the solution. On our side, we have explored a few sequences leading to unorthodox mates. We give to you, without pretension, our post Christmas puzzle: A game end with the move 6.d8=N mate. How did it go? Solution can be obtained by mail at: Marc Boulé: m_boule@hotmail.com. Marc and André

Stanislav Páral: Hi, I´ve find your puzzle as late as this month. After two days hard work I did not believe in any solution, but because I am coaching the team of young chess-players in our club, I give this puzzle to them as a homework. And in the next lesson after a week one pupil brought this: [Correct solution given]

Walter Zampieri: [Correct solution given]. It took me around 20 minutes; until I figured out that it had to be the other Knight that had to back to e8.

John Merlino: [Correct solution given] Basically, 5 of White's 6 moves must be pawn moves. The hardest part is deciding which pawn moves up the board. I figured it must be either a rook pawn, or a pawn in front of the queen, allowing the one supporting piece the one extra move. The queen seemed the most logical, so I tried many variations of that with no success. Then I tried the rook pawn (h being "closer" to the Black King), and it was fairly easy after that.

Joshua Green: [Correct solution given]