Puzzles needed for tactics trainer

Here is a tactic that black misplayed, although his position is poor, it went from bad to worse quickly. [also, I didn't mean to diagram it as a puzzle which gives black's errors as the 'solution' but a quick look makes it obvious what is happening]

For tactics trainer, can White get both moves right? If you're trying to do it fast, you might grab the wrong material or play a patzer's check!

Thankyou edvinj

63rd puzzle http://www.chess.com/tactics/server.html?id=363825

White's 30th, http://www.chess.com/echess/game.html?id=29460748

and 

I think this would be an excellent endgame for tactics trainer after black plays the natural-looking [but losing] Be4.

After black eats the A pawn with his bishop, it is drawn, otherwise white has all the winning chances.

edit: I suppose this could be called ambiguous since the other variation is still winning for White, so maybe it should just be a one-mover after 37 a6. But since White can easily blow it I think it works. The next diagram probably works better later in the game.

edvinj

http://www.chess.com/echess/game.html?id=16869364

There were many things I had to try to change such as the second move ambiguity. By moving the rook on f1, Nf6 was no longer an alternative winning second move. 

64th puzzle http://www.chess.com/tactics/server.html?id=235977 

65th puzzle http://www.chess.com/tactics/server.html?id=322589 

A few moves later from the actual game is probably a much better, and harder, tactic. Again, the natural looking move ends up drawing instead of winning, even with white's King on d6 and Black's on a7!

Katonas,

First off, let me say that I can appreciate the amount of effort that must be involved in managing the Tactics Trainer. Addressing all the submissions in this thread alone must be exhausting. Thanks for your comments.

But I have a few comments of my own. This thread could spawn another forum on the nature of the Tactics Trainer, the definition of tactics, and the use of computers in analysis. 

I don't have easy access to an engine, but I was able to get Fritz to look at the position after 1. Ra2. It found 1....Rxg2 after a short time (but not immediately), with the only evaluation as mate in 9. I think the next strongest move was +6 or +4, something like that. So even though ..Rxg2 is a forced mate, 1...Qe7 is still considered a winning move? I think most humans would at least look at the capture before the queen move, and I would not consider ...Qe7 a tactic. It takes black two or three moves (..Qe7, ...Qh4 {I assume that's the idea, although maybe Qg5 first is a finesse}, and ..Rg6) before he is even threating to execute what I would call a tactic with ...Qxh2+. 

This is just my opinion, and I certainly don't mean to dictate how the TT should be managed, but it's the Tactics Trainer, not What's The Best Move. I can understand not wanting any ambiguity and avoiding complaints from the users, but Rxg2 is the tactical solution, not Qe7. Before computers, a lot of tactics compilations were taken from actual games (Like the Informant series), and they had to be checked by hand (if the editors didn't just accept the notes from the titled players). I also think there is a point at which the intent of the TT becomess lost to the desire to avoid ambiguity.

For example, in the aforementioned Qe7 line, the rook lifts ..Rg6 and ...Rg5 are equivalent. It wouldn't matter to a human in an actual game which one is played. The idea is to play the queen to the h-file, lift the rook on the g-file, play Qxh2+, and then check on the h-file with the rook next move. But for the TT, one of those rook moves would have to be removed from the solution to avoid ambiguity? I think the TT should be able to accomodate such ambiguity, instead of asking submitters to accomodate the TT as it is. 

As  for removing some of the alternatives, I suppose I can put a pawn on h5 to eliminate the Qe7 line, but that seems very contrived. Why would Black play his pawn to h5 in that position? Again, it seems like we are serving the needs of the TT, rather than the other way around. The other alternatives are not as forcing as the line in the game, and the Bh3 and Bg2 line is definitely the strongest. It's part of a forced mate in 9. How much weaker do the alternatives need to be? And don't different engines give slightly different evaluations? It seems somewhat arbitrary to pick a number like +2 to separate acceptable lines from nonacceptable ones. And if it were up to me, I would stop the solution at ...Qh3. It's clearly won for Black at that point. I certainly didn't see 11 moves deep during the game. I just looked at Bf1 and Bd3, and that was good enough for both me and my opponent. And no reasonable human would sacrifice his entire army just to postpone mate for another six moves. At least, no human I would enjoy playing. 

And one final point (phew!) is that this game was played before anyone even knew what the Internet was. So there is no link to provide. 

Just a correction: I think it was only a forced mate in 9 if white took the rook. Fritz suggested something like Ne3 instead, and it was still a +6 evaluation for Black. But again, it just seems silly to consider moves like Ne3 when they don't even save the game for White. Any human would ask "what happens on Kxg2 ?"

Black's 17th could be considered ambiguous - I think virtually everyone will take the bishop there instead of leaving it, but this could be a Mate in 1 if you want to give the tactic after Black's blunder.

Thankyou edvinj,

Black's 24th, http://www.chess.com/echess/game.html?id=29417982

A lovely puzzle.

66th puzzle http://www.chess.com/tactics/server.html?id=467141 

edvinj, I love this puzzle

67th puzzle http://www.chess.com/tactics/server.html?id=258863 

Unfortunately   http://www.chess.com/echess/game.html?id=25011688 has alternavives to 54.Kf4 and so you are correct, it isn't conclusive enough. 

Thankyou for posting your submissions in such a thoughtful way, it saved me a lot of time.

Powerlevel,

68th puzzle  http://www.chess.com/tactics/server.html?id=118926 

69th puzzle  http://www.chess.com/tactics/server.html?id=281985 

That perpetual is nice.

chapablanca, I'm only one of many tactics approvers, and an inexperienced one who isn't very good at tactics at that, so I'm not the one to persuade when it comes to changing things. I agree with your sentiments, indeed I feel saddened everytime an ambiguous but beautiful puzzle is deleted from tactics trainer. Several approvers are deleting many wonderful but ambiguous puzzles each day, but I believe this is necessary. I do know that I've been very annoyed at times when playing tactics trainer after losing 16 points for playing the wrong winning move. In this particular thread, I'm looking for puzzles that are beautiful, educational, and unambiguous. 

Thanks Katonas.

About the second game, http://www.chess.com/echess/game.html?id=16869364

I think there was an option to start one move earlier than in the two problems you added, and then there would have been two unambigious moves as well. But the modified problems are good too.

edvinj, unfortunately I don't think it would be conclusive enough.

I tried starting one move earlier in the modified approved problem but for some reason it doesn't work.

NajdorfDefense

Nice idea to post in a different colour. It made your puzzles easier to find.

Shelten v Rimple  : unfortunately when the pawn promotes on b8 it has a choice which makes the puzzle ambiguous.

Newman v : unfortunately according to Houdini 2.a7 +6 was as good as 2.Bd3 +6. There are alternative moves later on as well 

A few moves later puzzle : 2a7? drawing line puzzle, unfortunately 3…g4 draws as well as 3…Kxa7. However, 

I'm not sure this is conclusive enough but could be used by providing a link to its conclusive continuation puzzle

71st puzzle http://www.chess.com/tactics/server.html?id=66812

70th puzzle http://www.chess.com/tactics/server.html?id=356545 

OK, I see your point. I couldn't find any good ways to change it from the initial starting move either.

Thanks for adding the problems. It will be interesting to see what ratings they get.

NajdorfDefense,

black17th puzzle: unfortunately 1 move problems are no longer being added to tactics trainer for a variety of reasons.

However with a bit of tweaking there is a nice perpetual problem. I had to remove the c8 bishop to prevent an alternative move attacking the queen. 

72nd puzzle http://www.chess.com/tactics/server.html?id=239507 

Is this one good? (I'm in NY, so I can get computer analysis from chess.com, but I can't analyze other moves with a engine.)

Link to the game: http://www.chess.com/livechess/game.html?id=327139626

Actually, it gives +12.6 for  2. a7. Not that it matters if the rest is unhelpful.

Going 24-ply you get +6.5 for both. Going further 2. Bd3 gets up to +9 which is still 3 points behind. The important thing is that Bd3 still allows White to blow the victory by playing very normal-seeming moves like the later a7??

Probably too long a string to play out for tactics trainer anyway, but maybe the stronger players would appreciate seeing that endgame position as GM Benko did. Probably makes more sense for one of the FM/IMs to do a column/quiz about it than tactics trainer, or used for Chess Mentor.