Mate in two (634)

White in two    by I. Lacny 1st place, W. C. Composing Tourney, 1972-5

A kaleidoscopic sort of problem with all of sorts of checkmates and temptations. Can't see a strong theme. Most action surrounds the choices of capturing on e7 and of course all the black pawns are very active. A very enjoyable problem to solve!

Cyclic shift is what the author is calling it....."The extraordinary 634 shows a 5 fold cyclic shift of the defensive motives of five Black defenses  ( guard,capture of threat piece ,unpin,unblock,cutting White line of guard) as they defeat the different threats of try and key"......I seen the key on this one but still enjoyed finding the rest of it...If you were post the position with the key and stated mate in 1 move after Black moves what would you call the puzzle.

That's the sort of modern "scheme" I am not strong at. It's like modern art. Once you know what it means, it starts to grow on you .... or not

If you create a problem where black moves first you should indicate it by adding half-a-move. Thus, #1.5. It is not common because they are easy to solve. However, when you state #1 and you can prove it is black's move then it is the same as #1.5.

To illustrate the use of the half move numbers in the previous post, look at the following puzzle which consists of 2 parts. It's a cheeky puzzle, as you will have a hard time solving the 2nd part but I will explain it later. Note: "=2" means "forced draw in at most 2 moves" (might also be 1 move).

this looks like a figure out how the W K got in there,...for the forced draw Pe4 white has one more move unless Black makes it none with E.P. capture or pe5  The 1.5 part I am trying to figure out

I guess 1..... pf2  2.Pe4  f pawn captures e.p.

Not quite! Black will not help by playing e.p. in the second part of the problem but instead promote: ... f1=Q 2. e5 Nc3#. But as said, the 2nd part is cheeky and actually quite tricky and advanced as well.

Let's first go back to part 1, the forced draw in 2 moves. This problem is a bit different from normal checkmate problems which always end with a white checkmate move. A stalemate problem can end with either a white or a black move while the assignment remains "=2" in both cases. That is because the optional black move is at the tail end of the solution. If black had been on move in this part then the assignment should have been "=2.5".  Note that in all cases white plays 2 moves, the 1st digit in the assignment. Something to remember!

The 2nd part is trickier. "=1.5" Indicates that black starts and white plays the next move. After that, an optional black move might follow at the tail end, but in all cases white plays just 1 move. However, there is a complication because you can prove that black cannot be on move in the diagram (white has no last move) which implies that white must start instead of black! This means that white must still play just 1 move, followed by an optional black move. You might say that "=1.5" has been changed to "=1" by the retrograde analysis (see my previous post). Q: Why does it not change to "=2"? A: Because the 1st digit always determines the number of white moves and it cannot change from "1" to "2". Conclusion: the 2nd part of the problem says you must draw in 1 move with white to start!

If you understand the above you have done your job and have a good understanding of full and half move assignments in common problems. What comes next is an advanced application of the rules and is taken serious by some and not by others. For me it is mostly fun though there are also actual chess rules involved.

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You can now see a contradiction between part 1 and part 2. How can there be different solutions for these 2 problems? If the "=2" problem has one 2-move solution then why wouldn't it also have the 1-move solution of the (adjusted) "=1" part? The reason it can't is because part 1 and part 2 are actually completely different problem types. Part 1 is a simple orthodox draw-problem with the solution 1. e4 Bd5 2. e5! ~ stalemate, but part 2 is a retrograde problem. And it is a retrograde problem because we had to do retrograde analysis to find out that black could not be on move and we changed that duty to white! In the first part that was no issue because there are many legal last moves for black for instance by capturing a white piece. Q; What does it matter that the 1st and 2nd part refer to different problem types? A: These problem types have slightly different rules. The difference is minimal but happens to be critical in this particular duo problem.

In the chess laws is an actual rule about dead positions and it applies to all chess games even the ones outside FIDE competitions. It says that a game terminates in a draw at the very moment it is sure that neither side can be checkmated even with the worst play. So, besides stalemates, that would count as a forced draw in problems with "=1", "=1.5" and "=2" assignments. Only it does not apply to part 1 because the Composition Codex excludes the dead positions from "normal problems" with common instructions. However, the same Composition Codex includes the dead rule for retrograde problems. In casu, the dead rule applies to part 2 of my duo problem and not to part 1! How then do I solve the part 2 assignment? Not by starting with 1. Pe4 because the position is not yet dead after 1. ... Bd5! It is still possible that somebody gets checkmated and white must play 2. Pe5 to assure a draw. But that is one white move too many in part 2! On the other hand, after starting with 1. Pxf3! the game is certain to end in a draw whatever moves are played and therefore immediately ends as a dead position after 1. Pxf3! Note that part 1 cannot be solved in this way because there is no dead rule and it would take 3 moves to reach a stalemate position when black refuses to cooperate.

As said, you are forgiven if you don't understand the latter paragraphs but you may decide at some point in your life to look into the retrograde issues! Good luck!

I think this adds up. Normally a stalemate stipulation asks for one player to always administer the stalemate (e.g. white in directpat), but that's specifically excluded by your stipulation

I think the half-move issues have never been quite resolved in combination with 'on move' changes by retro-analysis. For instance, everyone accepts that an on-move change in a #2 is effectively a #2.5. Is that the same for "=2"? Is it the same for helpmates with built-in half-move specifications? There is a potential difference between the side with the assignment to draw (the side who wants it) and the side actually delivering the last move. How does that play out? There should be a difference between a dictated half-move and one that occurs by retro-analysis. Do you happen to know a reference on those things? Btw, whatever the correct stipulations for my duo-problem are, the 2 solutions will continue to exist (under the joke-convention).

Speaking of (un)decidability

Well my only reference is Codex Article 15 together with Footnotes 9 and 19. The codex talks about d# with White to play and win, but this is just “an example” so we are up in the air again. But your logic was quite clear, given a reasonable interpretation. =n is fairy anyway. Basically in a help stipulation someone should lose a move, in a competitive situation Black should gain a move

OK, we are where we are.

I found the link to my first article on the incompleteness of the basic rule system and the proposed "billion move repairs". Probably not all that interesting to you but it gives an answer to the question what to do when you only have the basic rule set. I propose very high termination boundaries to stay out of reach of competition rule sets with lower values.

https://www.chess.com/forum/view/endgames/basic-rules-of-play-are-incomplete#comment-44421552 

Ok will check out your billion move post. Is the Lacny diagram legal?
The other #2 video posted. Who’s the composer? It really deserves its own thread instead

The problem posted by the O.P. appears to have an illegal pawn formation, based on possible pawn exchanges and the fact white still has a queen, 2 rooks, 2 bishops, and 2 knights.

Usually I check out legality in posted diagrams but this one came from the printed tasks book in sameez1's library. Didn't expect an illegality there. Edit: It is indeed LEGAL!

The video has its own thread - at least 3 of them. Most good problems are reproduced ad infinitum on this site or they are never posted at all. Most visitors are kids and copycats and both. 2020.

The problem itself was very easy to solve, but there is an additional problem:

In a chess composition, every piece on the board must have a reason for it's existance, but there are multiple pieces that can be removed, while still keeping the functionality  of the puzzle intact.

Yes, every piece in a composition must have a function. The functions of a composition though are not as narrow as in a game which is only about achieving the goal. Every composition portrays the expression of a theme, not just in the main line of the solution, but also in the variations and in the tries. And even in the "set play" (the lines after white "passes" on its first move). Read what the OP sameez1 wrote about that theme:

Cyclic shift is what the author is calling it....."The extraordinary #634 shows a 5 fold cyclic shift of the defensive motives of five Black defenses  ( guard,capture of threat piece ,unpin,unblock,cutting White line of guard) as they defeat the different threats of try and key"

Everything in this description is a justification for adding units to the position. I am pretty sure that removing units from the diagram would remove some of the thematic content somewhere though I haven't verified them all myself. Composing problems is art and science together and a lot of hard work on top of it! 

Interesting. I'd be curious what a master or grandmaster composer would say about the puzzle.

I like solving chess compositions, but the puzzles rarely have any additional info outside of the board diagram.

Also it's more of a side hobby, so I usually just get them ad hoc off the internet, on occasion, rather than any sort of serious study.

Arisktotle is right about the OP problem, of course. Its composer, Lacny, is a famous name in the chess problem world who passed away in December last year. The problem gained a 1st Place in a major competition and it would've been well scrutinised by experts, so the chance of it having a serious flaw is very slim.

The position is legal. Black's pawn structure requires 5 captures and White is missing 5 Ps, some of which could have promoted to replace pieces that were captured earlier. The BPs on the f-file came from the g- and h-file, and this would allow the WP on f6 to retract to f2 without needing to have captured anything.

The theme shown is a highly unusual one that's kind of suitable only for experts, who may understand it without necessarily liking it. The idea is that you have to examine the 5 variations following the try-move 1.fxe7?, and compare them with the 5 variations after the key, 1.Rxe7! It's a standard device in modern compositions to show changed play between a try and the key, but this problem shows a rare type of change that "subverts" your expectation.

I think it's illegal.
White missing: PPPPP
Black missing: QP
Black pawn captures: bxcxd, cxd, dxe, gxf = 5, so bPh never left that file.
White pawn captures & promotes axb=X, b=X
+ either gxh while bPh promotes, or bPh was waylaid to clear path for wPh to promote.
Ok so far *BUT* original pawns on f-file have passed one another without capture. so this is illegal, I think.