Favourite Chess Tactics/Games/Random Positions

[hamish olson]

I haven't tried to get the position from the start, but I think the pawn has to be on f5 on the basis that if it were possible for the pawn to be on f4 then it's also possible for the pawn to be on f5 and therefore the only unique solution is for the pawn to be on f5. (I'm hoping this makes at least some sense but I've not done many of these before so it might be nonsense?)

[Calum MacQueen]

Can it not be either? I'm struggling to see why you can't lose the dark squared bishop on g3, the knight on f4 and get the light squared bishop taken by black's bishop?

[Calum MacQueen]

Oops, that's embarrassing. The dark bishop can't get out so you must give the knight on g3. Which leaves you with a LSB to sack somewhere. But why can't you go Bf3 then exf3 and f4 would give the position with the pawn on f4?

Maybe I'm missing something and the only way you can get the pawn to the f-line is by exf5? Can't see it though...

[Calum MacQueen]

I've really got to think things through before string posting in case I look like an idiot...

the pawn is on f5. And here's why.

So, the bishops on f8 and c1 can just get captured by knights, I don't really see why they aren't there but I'm not sure this impacts the solution.

The black knight has to get sacrificed on g3 as it is the only way to get a pawn there which means black's light squared bishop needs to get sacked on either f3 or f5 to get a pawn to the f file.

How do you do this though? You need to get the light squared bishop out but the only way this is possible in the diagram is for white to play Bc6 at some moment. The white knight can't do this because that has to be taken on b6. For this, you obviously need to move the white light squared bishop and, ta da, this means you have to move your e-pawn making exf3 impossible. Hence, the bishop must have been taken on f5.

Phew, 3rd time lucky

[Graham Kerr]

Back to the OP's OQ, my favourite game has to be this one:-
[pgn][Event "London casual"]
[Site "London"]
[Date "1912.??.??"]
[Round "?"]
[White "Lasker, Edward"]
[Black "Thomas, George Alan"]
[Result "1-0"]
[ECO "A83"]
[Plycount "35"]
[Eventdate "1912.10.29"]
[Eventtype "game"]
[Eventcountry "ENG"]
[Source "ChessBase"]
[Sourcedate "1998.11.10"]

1.d4 e6 2.Nf3 f5 3.Nc3 Nf6 4.Bg5 Be7 5.Bxf6 Bxf6 6.e4 fxe4 7.Nxe4 b6 8.Ne5 O-O 9.Bd3 Bb7 10.Qh5 Qe7 11.Qxh7+ Kxh7 12.Nxf6+ Kh6 13.Neg4+ Kg5 14.h4+ Kf4 15.g3+ Kf3 16.Be2+ Kg2 17.Rh2+ Kg1 18.Kd2#
1-0[/pgn]

[Geoff Chandler]

Hi Graham,

That game has a fascinating history attached to it.

It has been reprinted so many times that errors have crept in about when it was played,
where it was played, who played it, what were the conditions, what was the exact move order
(the are 9 different versions in print of how the first 9 moves were played!) and how did it end.

The years differ from 1911 to 1913, some sources claim it was Emanuel Lasker,
it was not a blitz game and Lasker (Edward) played 18. 0-0-0 mate and not 18.Kd2.

It would appear that the majority of these mistakes except the one that it was played
by Emanuel have come from Edward Lasker himseld when reprinting the games in various sources.

Even Alekhine and Bernstein have chipped in spotting a quicker mate if White plays 16.0-0 or 16.Kf1.

Edward Winter has sorted it all out finally including a picture of the actual game score in Ed Lasker's own
fair hand.

<!-- m --><a class="postlink" href="http://www.chesshistory.com/winter/extra/laskerthomas.html">http://www.chesshistory.com/winter/extr ... homas.html</a><!-- m -->

[Geoff Chandler]

Hi

The solution has come from the RHP lad.
--------------

Solution: White and Black both made two pawn captures. The pieces they captured were a wN, wBf1, a bN,
and bBc8. (Bf8 and Bc1 could never have left their start squares.)

The Bishops had to be captured on light squares, so they were captured on c6 and f3 or f5. Bf1 must have
been captured first on c6 to let Bc8 out, which was then captured by white's e-pawn.

But this means white's e-pawn did not capture until after Bf1 died. Therefore, it moved forward without
capturing to let Bf1 out. Bc8 could not have been captured on f3, so it was captured on f5, and thus white's
pawn is on f5.

----------------------------

Of course I figured all that out.

[Graham Kerr]

Wow, funny you say that Geoff, ISTR first coming across it when it was in the Frtiz 2 database, then losing it again for many years. The post was sourced from the Chessbase Megadatabase 2012, but i also seemed to remember 0-0-0 was played. I guess it's also been changed for 'artistic value', when it already has plenty...

[George Murphy]

Accidents happen – with varying effects.

Often, ‘chess puzzle’ is synonymous with ‘composed chess problem’. Paradox, Tries (near solutions), and Cooks (unintended solutions) are characteristic of chess problems. So, the first requirement of problem solving – cryptic or composed - is to understand exactly what it is the composer is asking.

The two ‘solutions’ submitted seem incompatible but are in fact complementary. One was declared correct, the attached commentary indicating the puzzle was intended to be cryptic – not composed. I decided to keep my head down. However, …

The narrow choice between e3 and e4 risks ambiguity. As locations, they are in themselves not obviously significant; it is their colour complex that matters. Whichever White Bishop is to be added may occupy any legally accessible square of its colour. Thus, there is an array of solutions to choose from – not a unique one. I suggested e6 might be an improvement over e4 to underline this. The former is more plausible because it promises Virtual Play (a variation that follows a Try). I hinted heavily when I said the rubric permitted the use of Retro-analysis and gave a sample variation. I held back one detail but had the rug pulled from under me when the intended solution was announced without notice.

Endorsing one solution does not preclude another. T.R. Dawson (1889-1951) promoted Fairy (unorthodox) chess. He exploited Retro-analysis to prove both the legality and illegality of positions. Examples of his thinking may be accessed via the BCPS link on the CS Home Page: I suggest ‘irreal regions’ is notable.

Placing a light squared Bishop on e4 (or e6) is a Try that fails because of illegality – hence the second solution. By elimination, the White Bishop must occupy e3 – a black square.

This Illegality needs to be proved independently of the intended solution to avoid circularity. Since the Black King is restricted to white squares, he must account for the disappearance of the last light squared White piece from the board. (The same process of reasoning used to produce the intended solution.) Since it is illegal to replace a captured piece on a chessboard - except via a Pawn promotion - there cannot be a White Bishop on e4 (or e6).

So, there are two, complementary solutions to the ‘chess puzzle’. This is such a neat and symmetrical outcome that it is difficult to credit that it is coincidental and not by design. Almost any composed problem solver would see e3 and e4 as an axis round which their positive and negative properties spin in counterpoise - an image that may be more aesthetic than cryptic, but not beyond alert practical players?