TTHHEE PPUUZZZZLLIINNGG SSIIDDEE OOFF CCHHEESSSS Jeff Coakley RETRO WORLD V: Momentary Lapse In Time number 191 June 30, 2020 Retrograde analysis is a form of logical reasoning in which past events are deduced from details in the present situation. In chess, its common use is to determine the move or moves that led to a given position. This column presents eight last move problems, six of the usual type plus two disguised as rebuses. Four retros by Werner Keym are featured, including one from his new book Anything But Average. Before starting our investigations, here are a few notes from The Chess Detective’s Handbook, the classic work by renowned sleuth Harmonius Hound. When answering the question “What was the last move?”, be as precise as possible. A complete description of a move includes the square a piece moved from, whether a capture was made, and if so, what type of piece was taken. Moves are counted separately for White and Black. “Last two moves” means one turn by each side (W-B or B-W). Assume that the positions are legal, no matter how strange they may appear. A position is legal if it could be reached in a game following the standard rules. Rational strategy is not a requirement. If the scent is strong, the trail is not too long. See where it leads. We begin with a relatively easy problem by our guest artist, Werner Keym, a leading authority on retro chess from Meisenheim, Germany. The stipulation is to determine the last move played. However, it is possible to figure out the preceding move as well, although it is partially ambiguous with regard to the departure square or capturing. Given that provision, we could ask, “What were the last two moves?” Retro 45 w________w áBIwdwdwd] àdwHRdwdw] ßB)kdwdwd] Þdw)wdwdw] Ýwdwdwdwd] Üdwdwdwdw] Ûwdwdwdwd] Údwdwdwdw] wÁÂÃÄÅÆÇÈw What was the last move? The next retro is a game-like position from the land of Canucks. Happy Canada Day! (July 1) Retro 46 w________w áwdw4wdwd] àgp0whpip] ßpdp1pdpd] ÞHwdwdw!w] ÝwdPdwdwd] ÜdPdwdwHP] ÛPdPhw)Pd] ÚGw$r$wIw] wÁÂÃÄÅÆÇÈw What were the last two moves? Things get much trickier now. In the following three problems, all by Werner Keym, neither king is in check. Figuring out which side just Next up is a “Rex solus”. A solitary black king, alone without solace. Retro 48 w________w áwdwdwdwd] àdw)wdwdw] ßwdPHwdwd] Þdw)B$wdw] ÝwdPiwdwd] ÜIwdNdwdw] ÛP)P)wdwd] Údwdwdwdw] wÁÂÃÄÅÆÇÈw What were the last two moves? In his book, Werner Keym refers to the following masterpiece as his “best last-mover”. That says a lot from someone who has composed so many outstanding problems. As is often the case, to determine the last move, one must actually look several moves into the past. Retro 49 w________w áwdwdngwi] à0w0p0K0B] ßw0wdw0pd] Þdwdwdwdw] Ýwdwdwdwd] Üdwdwdwdw] Ûwdwdwdwd] Údwdwdwdw] wÁÂÃÄÅÆÇÈw What was the last move? (The last 3 moves can be deduced, with the second partially ambiguous.) Of all the problems in my Winning Chess Puzzles For Kids books, this is probably the hardest. Something near the end of Volume 2 to stump and/or inspire the keenest of the keen. Retro 50 w________w áwdRdRdwd] à0wdbdwdp] ßk)Pdwdw)] Þhwdwdw)r] Ýw!wdwdwd] ÜdPdwdN0K] ÛwdPdrdw)] ÚdwdwdBGw] wÁÂÃÄÅÆÇÈw What were the last ten moves? This column concludes with a pair of rebuses. Like most puzzles of this type, part of the stipulation is to determine the last moves. Usually, once a rebus position is decoded, the last move is obvious. But often the move must be determined first in order to assign pieces and colours correctly. The first rebus is the basic variety, definitely something average. Rebus 36 “very average” w________w áwdwdwdwd]aVg àdwdwdwdw]V ßwdwdwdwd]E Þdwdwdwdw]rR Ýwdwdwdwd] Üdwdwdwdw]y Ûwdwdwdwd]Ge A Údwdwdwdw]reR wÁÂÃÄÅÆÇÈw Each letter represents a different type of piece. Uppercase is one colour, lowercase is the other. Determine the position and the last move. Rather than give away our goal in composing the next rebus, which might provide an unwanted hint to solvers, we’ll introduce it with a quote from the great Delta bluesman, Robert Johnson. I went down to the crossroads, Tried to flag a ride. Nobody seemed to know me. Everybody passed me by. Rebus 37 “Crossroads” w________w áwdwdwdwd]c R A Dr àdwdwdwdw]OS AcC ßwdwdwdwd]aO Þdwdwdwdw]co O Ýwdwdwdwd]c Üdwdwdwdw]CCr s Ûwdwdwdwd]ocod A Údwdwdwdw]R C r wÁÂÃÄÅÆÇÈw Each letter represents a different type of piece. Uppercase is one colour, lowercase is the other. Determine the position and the last six moves. Thanks to my good friend and partner in Rebusland Productions, Andrey Frolkin from Kiev. Three of his problems were selected for Anything But Average. Ain’t No Cure for the Summertime Blues SOLUTIONS Solutions are written in long algebraic notation, giving departure and destination squares. If there is a capture, the type of piece taken is indicated in parentheses. For more information about retrograde analysis, see Chess Mysteries in a Retro World (column 30). PDF hyperlinks. You can advance to the solution of any puzzle by clicking on the underlined title above the diagram. To return to the puzzle, click on the title above the solution diagram. Archives. Past columns are available in the Puzzling Side archives. Retro 45 Werner Keym 1995 Die Schwalbe w________w w________w áBIwdwdwd] árIwdwdwd] àdwHRdwdw] àdPHRdwdw] ßB)kdwdwd] ßB)kdwdwd] Þdw)wdwdw] Þdw)wdwdw] Ýwdwdwdwd] Ýwdwdwdwd] Üdwdwdwdw] Üdwdwdwdw] Ûwdwdwdwd] Ûwdwdwdwd] Údwdwdwdw] Údwdwdwdw] wÁÂÃÄÅÆÇÈw wÁÂÃÄÅÆÇÈw Last move: 1.b7xa8(R)=B+ position before last move Black is in check by the bishop on a8. No discovered check was possible so the last move was either a7-a8=B+ or b7xa8=B+. The last move was not a7-a8=B+ because Black would have no legal move on the previous turn. The black king would be in an impossible double check on b5, d5, or d6. So the last move was b7xa8=B+. The piece captured had to move to a8 on the previous turn, otherwise Black had no legal move. It was not a bishop or knight because they had no square to move from. It was not a queen because she would already be checking the white king if she came from a7. Therefore, a rook was captured. Black’s previous move was ...Ra7>a8+ which may or may not have been a capture. Retro 46 J. Coakley 2004 Winning Chess Puzzles For Kids w________w w________w áwdw4wdwd] áwdw4wdwd] àgp0whpip] àgp0whpip] ßpdp1pdpd] ßpdp1pdpd] ÞHwdwdw!w] ÞHwdw$w!w] ÝwdPdwdwd] ÝwdPdwdwd] ÜdPdwdwHP] ÜdPdwdwHP] ÛPdPhw)Pd] ÛPdPdw)Pd] ÚGw$r$wIw] ÚGw$rdnIw] wÁÂÃÄÅÆÇÈw wÁÂÃÄÅÆÇÈw Last two moves: position two moves ago 1...Nf1-d2+ 2.Re5-e1+ Black is in check from the bishop on a1. The last move had to be a discovered check because the bishop could not have moved to a1 to give check. It would already be checking along the same diagonal. The last move was not a discovered check by 2.b2-b3+ because with a white pawn on b2, there could not be a white bishop on a1. The last move was not 2.c3-c4+. The only piece Black is missing is a light-square bishop. That means the doubled white c-pawn captured the black bishop on c4 (light square), and the pawn could not have been on c3. The only other possibility is Re5-e1+. This move was not a capture because the only missing black piece was taken on c4. That means that White was in check from the rook on d1 on the previous turn. The black move had to be a discovered check because the rook could not have moved to d1 to give check. It would already be giving check along the first rank. It was not a promotion by 1...e2xd1=R+ because black still has all eight pawns. The discovered check 1...Nf1-d2+ could not be a capture. There was no pawn on d2 because the white d-pawn captured on c4. White is missing two pieces, the light-square bishop and the e-pawn. The bishop was taken on c6. The white e-pawn was captured by Black at some point on the e-file. The only missing black piece was captured on c4, so there is no way the white e-pawn could have promoted on d8, because it could not get to the d-file without a capture. Retro 47 Werner Keym 1980 Die Schwalbe w________w w________w áwIwdwhkh] áK1wdwhkh] à0p0pdp4p] à0p0pdp4p] ßwdwdpdpd] ßwdwdpdpd] Þdwdwdwdw] Þdwdwdwdw] Ýwdwdwdwd] Ýwdwdwdwd] Üdwdwdwdw] Üdwdwdwdw] Ûwdwdwdwd] Ûwdwdwdwd] Údwdwdwdw] Údwdwdwdw] wÁÂÃÄÅÆÇÈw wÁÂÃÄÅÆÇÈw Last move: 1.Ka8xb8(Q) position before last move The only black piece with any reverse mobility is the e-pawn. The last move was not 1...e7-e6 because then the white king could not be on b8 with a black rook on g7. If 1...e7-e6 were the last move, the white king entered the 8th rank through g6 and the black knight was on h8 before ...g6 was played. With h8 occupied, there was no way for the white king to bypass a black rook. So the last move was by the white king. It had to be a capture of a piece that just moved to b8, otherwise Black had no legal move on the previous turn. The piece captured was a queen or rook. Black has both knights on the board and a bishop could not be on b8. So the two questions are: Was a queen or rook captured? Did the king take from a8 or c8? In any case, the previous black move had to be a capture on b8.