Such tactics are NOT ok as far as I understand, and as katonas has said on the first page - "We're gradually deleting ambiguous problems...".

msjenned, tactics trainer puzzles with alternative lines with a strong advantage are gradually being deleted.

Thanks shoopi, for some reason I didn't see your reply to msjenned until after I'd posted.

Understood on your requirements stated, but personally have yet to see your gradual deleting. I will let you know if I spot those.

I would guess 1/4-1/5  of the current problems should be deleted or edited. Considering there are almost 50,000 problems, and the deleting/editing is done by volunteers (I pay for my membership like everyone else), there will be many ambiguous problems in tactics trainer for some time. I usually delete ambiguous ones I come across whilst playing tactics trainer in both rated and unrated modes, but I prefer to spend time discovering new unambiguous puzzles, and improving my game.

Understood on the number of puzzles. Who does the screening of TT, or who shall I report ambiguous puzzles too? Technical Staff?

Click on a red flag at the top right if there is one. I think if enough people click on the red flag the problem is removed from the pool of problems and added to the 100,000+ problems in the approver pool. I don't spend much time looking at the problems in the approver pool as around 90% need deleting, and only around 1% are problems that I really like (the 90% of bad problems however, once deleted, provide a space to put problems such as we have seen in this thread. However thanks to this thread I am learning to fix ambiguous problems, and extend 1 move or inconclusive problems so I am finding myself deleting a much lower proportion from the approver pool, and the active tactics trainer pool.

Otherwise make a comment and eventually an approver with time to spare (not me) will see the problem and make any necessary changes.

1/5 problems needing deleting or editing is probably a bit pessimistic unless you take into account all the single move problems (have difficulty finding an appropriate rating, and often have very short time limits) especially hanging pieces, and inconclusive (and so poorly educational) problems. Note my criteria of a second best move of <0.3-1.0 is stricter than the current tactics trainer guidelines of <2.5, but at least if the guidelines become stricter in the future our problems won't need to be deleted/edited.

Noted.

Anyone with some more beautiful unambiguous problems from their games? I'm particularly keen to find some more endgame problems. Analyzing your games with an engine is also a great way to improve.

Unfortunately in puzzle 1, powerlevel 2.Ne5 (+4.27) is a winning alternative to 2.Bxf7 (+3.51) and 3….gxf6 (-11.8) is much weaker than several moves eg. 3….Bxf2 (-3.40). 

In puzzle 2, 1.Kb8 ,  2.Kc7 and 2.Kc8 and 12.Qg3+ (mate in 10 instead of mate in 5 with Qe7+) are winning so the problem has to start late and finish early. I love the move 6…Kf5! to gain the extra tempo to queen first. It’s a shame a second drawing puzzle couldn’t be created for white starting with 6…Kf4? because white would have a choice of drawing moves.

32nd puzzle http://www.chess.com/tactics/server.html?id=290983

thankyou for such a great endgame puzzle.

I just did a very nice defensive move in one of my online games, I will post it when the game has moved on a few moves in case seeing the computer evaluation counts as cheating.

Ok ill post it now opponent just resigned :)

It's move 28 in this game- http://www.chess.com/echess/game.html?id=55466364

EDIT: Removed puzzle, is flawed, see comment below

2. Re3 defends.

How about 2...Re1+ in regards to last comment?

No...the rook on e3 blocks the e-file so Re1 is illegal

I missed 2.Re3 actually, and I dont think black has anything better than 2...Qxe3 3. fxe3 Rgxf8 4.Rd7+ Re7, which is the same material balance as after 1...Qxd1+, so this puzzle is flawed.

There might have been a tactic from White's perspective in that game then but he only wins Q for R+B which isnt really enough for a tactic.

Powerlevel_9001 puzzle 1 looks like it should be ok but there isn’t an FEN for the start of the puzzle I can copy and paste into an engine. Puzzle 2: unfortunately there are lots of alternative winning lines, although 3…axb4 4Kxb4 Kxf6 is a potential puzzle it isn’t conclusive enough and starting a puzzle with an easy move causes problems with a puzzle achieving a correct rating on tactics trainer. Puzzle 3 is ambiguous : 1…Rxg3 (+9) and 1….Nxb3 (+7) alternative. Even after removing 3 of black’s minor pieces to make 1…Rxg3 the only good move, after 2Kh1 Rxf3 3Qa6+ there is little to choose between black’s moves. Puzzle 4 1….Qf2 (+10) is a winning alternative to 1….Kg7 (mate in4). However after 1…Qf2 2.Qxf2 provides a nice easy puzzle :

33rd puzzle http://www.chess.com/tactics/server.html?id=201799

With a rook on a1 to prevent alternative advantageous lines and an extra knight on e2 to prevent Qf4+

34th puzzle http://www.chess.com/tactics/server.html?id=297937

Piphilologist, I was hoping Re3 could be the first move of a puzzle for white but unfortunately Kf1 also defends after Qd2. Unfortunately moving the starting position for the white king to h1 doesn’t seem to provide a usable problem. There don’t appear to be any obvious tactics after 2Re3 Qxe3 3. fxe3.

Reminder to everyone. You don’t need to post a diagram. A link to the game and move number of the start of the puzzle allows me to use the ‘get PGN’ button to check your puzzle. However please exclude any alternative winning moves with an engine at every step of the puzzle. 

shoopi, your last problem has spawned another

35th puzzle http://www.chess.com/tactics/server.html?id=300497

Heh funny, that's one of the variations I analysed from one of the tactics.

Here's a simple endgame (though it requires some precision, as always), altered from one of my games:

Shoopi is an impressive person.

Thankyou shoopi, impressive as ever

36th puzzle http://www.chess.com/tactics/server.html?id=247625

variations :

39th puzzle http://www.chess.com/tactics/server.html?id=154091

38th puzzle http://www.chess.com/tactics/server.html?id=248793

37th puzzle http://www.chess.com/tactics/server.html?id=91717

Thankyou Powerlevel_9001, nice attack

41st puzzle http://www.chess.com/tactics/server.html?id=456661

 variation

40th puzzle http://www.chess.com/tactics/server.html?id=364489

 StMichaelID

 http://blog.chess.com/StMichealD/bonus-puzzles

problem 1 : unfortunately there are several ways to win so the problem is ambiguous as far as tactics trainer is concerned. Similarly in problem 2 there are 2 mate in 10’s as alternatives to the mate in 4.

If you come across any unambiguous problems in your games you think might be suitable for tactics trainer then please post on this thread rather than sending me a message.