Tactics Analysis #6

Current Puzzle rating: 2284 (+20)
Current puzzles completed: 1275 (+65)

Position #1

https://lichess.org/training/GbeNE

I can honestly say I had no idea what the idea here was, either the first time I saw the position or replaying it just now. Only now after some analysis do I see the ideas - the undefended bishop on c4, the pinned pawn on d4, the weak square/knight fork on f3, the threatened knight on d7 (OK I did see that one). We have to put all this together to find the winning sequence - on a good day I might find this as a puzzle - I don't think I would find this in a game at all.

SOLUTION
1. ... Ne5 2. exf7+ Kh8 3. Qd1 (or pretty much anything else) Nxc4

Position #2

https://lichess.org/training/BUoH4
White's winning idea - promote a pawn - seems clear here. The question is really how best to do this. There are 2 candidate moves in my opinion - f6 and Kg6

The problem with Kg6 (spoiler: that's not the answer) is that after Ne7+ White can't make any progress. The engine continues 2. Kg5 Nc6 and White now has to move the bishop because he can't lose it, but the only options are f6 and g7 - otherwise he loses control of the Black pawns. So White ends up in his own way.

So 1. f6 it is, but then what? I of course looked at this move but couldn't calculate down the lines. If Nxf6, either capture wins, but Bxf6 makes most sense to me, with the White king protecting his pawn while the bishop goes to b2 and stops the pawns (e.g. 2. ... Kh7 3. Bd4 c2 4. Bb2 and eventually Black has to either allow White's king to g6 or move the pawns where they can be captured). If 2. ... Kf7, which the puzzle plays, h7 and the pawn can't be stopped.

SOLUTION
1. f6 Kf7 2. h6 c2 3. Bb2

Position #3

https://lichess.org/training/QZpmn
The key tactical element here is a simple pin - it's the first move that is particularly interesting to find here as it requires a bit of clearance to work. I think the other element to look for is the knight on c4 being defended only by the queen, as that proves important. Of course, looking for undefended or loose pieces is a standard tactical idea, but perhaps looking for these "expensively defended" pieces should be something I pay more attention to as well.

SOLUTION
1. ... cxd4 2. Nxd4 Bxc4 3. Qxc4 Rc8

Position #4

https://lichess.org/training/wUnc6

I see a few possible issues for Black. The knight on c6 is pinned and threatened, the kingside is undeveloped, and the lsb is attacked twice and defending once. To complete this position, we must spot that the White checks run out quickly after Nxc6, in order to be confident that we can launch an attack of our own.

SOLUTION

1. ... Bxe2 2. Nxc6 Qxg2 (also the move after 2. Kxe2) 3. Nd4+ c6 (and there are no more checks to worry about)