2) White has the threat of 40 Nxc7 and 40 Qh5+

3) White has the passed h-pawn

4) White has a powerful e6 knight but it can be challenged

5) White rooks has c-file pressure and can potentially transfer the rook on the kingside with Rg3

6) Black king is exposed and only the g7 bishop offer defensive cover

Candidate: 40 Nxc7, Qh5+ and Bh6

a) 40 Nxc7 Nxe4- all the pressure is off on the BK and c-file and White only has R and P for two minor.

b) 40 Qh5+ Kg8 41 Nxg7 (if 41 Qxg7 42 Bh6 Qe7 43 Rg3+ Kh8 44 Bg7++ Kg8 45 Bf8+! Kxf8 46 Qh8+ Kf7 47 Rg7 mate) (if 41 Qf7 42 Qxf7+ Kxf7 43 Nf5! Kf8 44 Nxd6 ) Nf8! 42 Bh6 Qf7 43 Rg3 Nxe4! 44 Rxc7 Qxc7 45 Ne6+ Nxg3 46 Qg4+ Kh8 47 Bg7+ Kh7! 48 Nxf8+ Kg8 49 Ne6 Bxe6

It has always puzzled me why people are so afraid of spiders. Okay, the ginormous hairy tarantulas I can understand, and the funnel web guy is pretty poisonous. Oh, and the Australian redback has a nasty habit of hiding in outside dunnies (aka toilets) and biting you on the ... erm ... well, you get the idea.

But why are people so afraid of household spiders? The little itsy-bitsies fellas for whom the height of carnivorous ambition is to eat a fly. The Mem will happily declare that a lion, bear or a tiger is cute - massive creeatures who would cheerfully tear or gnaw your arm off and then hit you with the soggy end. But she will run a mile and scream for male assistance when even the titchiest arachnid crosses her path. And she won't even watch that scene in Indiana Jones and the Temple of Doom.

The answer, I think, is that spiders have three specific traits that make them seem alien, other-worldly, strange.

First, they have eight legs. And that seems very odd to humans who have two of everything down the side and one of everything down the middle. But even I can't make a chess analogy out of that one.

Secondly, they are fast. Spiders can scuttle along at scale speeds of ... heck I don't know, but it sure seems fast when you are trying to peel your dearly-beloved off the ceiling.

But most importantly, spiders are trappy little so-and-sos. They don't go for the classic run-after-antelope-and-eat-it tactic which is the speciality of the cheetah and lion. No, they are so out and out sneaky that they catch their prey in sticky webs, and they slowly let their prey rot before they eat them. Yuck.

Today's puzzle is a fast-moving web-spinning tactic. Unlike yesterday's complete washout, it didn't take too long to spot the two sequences - 40. Nxg7 Kxg7 41. Qh5 and 40. Qh5+ Kg8 41. Nxg7 Kxg7. And then we intend moves like Bh6 and Rg3 and the black king would surely be caught.

That bit is the inspiration. Next comes the perspiration as we work through the details. The problem with web-spinning is that there comes at least one point when you give your opponent a free move. For example, take the sequence 40. Nxg7 Kxg7 41. Qh5

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It is black to move and we have invested two minor pieces into the attack. We need to find that mate, or snaffle back lots of material to justify our investment. With Qh5 we have made a non-forcing move. Black isn't in check and isn't threatened with instant loss of material. He has lots of choices, and we need to be happy that none of them allow him to escape.

From this position, Fritzie reckons that the best defence for black is 41... Nf8 42. Bxc5 Rxe4 43. Rg3+ Rg4 44. Rxg4+ Bxg4 45. Qxg4+ Kh8 46. Be3 Rxc1+ 47. Bxc1.

When I took a look at this, I got a similar line to <dzechiel>'s:

40.Qh5+ Kg8
41.Nxg7 Qxg7
42.Bh6 Qh7
43.Rg3+ Kh8
44.Bg7+ (and the Q drops after 44...Kg8 45.Bxf6+ Kf8 46.Qxh7)

But what I didn't understand from the game line was:

40. Nxg7 Qf8 gives white a host of options. My immediate pick was simply 41. Ne6 forking queen and rook, but Fritz prefers 41. Bh6 and 41. Qh5+. Let's look at the latter: 41. Qh5+ Ke7 42. Bh6

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<vaskokibika> Fritz thinks that 40...Bh6 leads to a mass exchange of pieces and a level (ish) position. White is, after all, already a piece down. This is one line:

40. Bh6 Bxh6 41. Qh5+ Kg8 42. Qxh6 Qh7 43. Rg3+ Kh8

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40 40 Qh5+ Kg8 41 Nxg7

a. If ... Qxg7 42 Bh6
a1. ... Qh7 43 Rg3+ Kh8 44 Qe8+
a2. ... Qe7 43 Qg6+ Kh8 44 Rg3
a3. ... Qf7 43 Rg3+ Kh7

All these lines look good for W

b. If ... Kxg7 42 Bh6+
b1. ... Kh7 43 Bf8+
b2. ... Kh8 43 Bg7+ Kg8 44 Qh8+ Kf7 45 Qh5+ Kxg7 46 Rg3+ Kf8 47 Qh8+ Kf7 48 Rg7# (or 43 .... Kxg7 44 Rg3+ Kf8 45 Qh8+ Kf7 46 Rg7#)

b3. .... Kg8 43 Rg3+ Kh8 44 Bg7+ Kg8 45 Bxf6+ and if B wants to play on he can delay # until move 51 (I think)

Even better for W

So unless I missed something it seems the N on g7 is immune. However, 41 ... Qf7 looks to hold the things together. B is still a N up and I cannot see a way through for W. At this point I look for plan B

How about 40 Bh6?
If 40 ... Bxh6 41 Qh5+ Kg8 42 Rg3+ Kh7 or Kh8 43 Rg6 wins

So perhaps 40 ... Nf8 41 Qh5+ Kg8 42 Bxg7 Nfxe6 43 Qxh8+ Kf7 44 Qh5+ Kxg7 45 Rg3+ (44 ... Kf8 45 Qh8+ Kf7 46 Qg8#) Ng5 46 hxg5 then
a ... fxg5 47 Rxg5+ Kf8 48 Qh8+ Kf7 49 Rxg7+ Kf6 50 Qh6# b ... Kf8 47 Qh8+ Kf7 48 g6#

And finally 40 ... Nxe6 41 dxe6+ Qxd6 42 Qh5+ followed by Rxc7 (or 41 ... Kxd6 42 Qg4+) and I think its winning

I havent looked at all the moves for B and maybe there's a defense which keeps B's material edge. I fancy 40 Bh6 is W's best try, but I have a feeling that W actully plyed 40 Qh5+. Now to find out.

Black threatens to eliminate the white knight when appropriate.

The rook on c7 is hanging but after 40.Nxc7 Bb7 Black seems to have improved his defensive prospects compared to 40.Nxg7, threatening 41.Nf5 and 41.Qh5+:

A) 40... Kxg7 41.Qh5

A.1) 41... Nf8 42.Bh6+

A.1.a) 42... Kh8 43.Bxf8+ Qh7 44.Qe8

A.1.a.i) 44... Bd7 45.Bg7+ Kxg7 46.Rg3+ Kh6 47.Qf8+ Kh5 48.Rxc5 (48.Qxf6 Nxe4 and White seems lost) Rxc5 49.Qxf6 and mate soon.

A.1.a.ii) 44... Qg8 45.Rg3 Qxg3 46.fxg3 (46... Bd7 47.Qd8 wins) Kh7 47.Bxd6 Bd7 48.Qf7+ followed by 49.Qxf6+ and 50.Bxe5 winning.

A.1.b) 42... Kh7 43.Bxf8+ Kg8 44.Bxe7 Rxe7 45.Rg3+ Rg7 46.Qe8+ Kh7 46.Rxg7+ Kxg7 47.Qxc8 + -.

A.1.c) 42... Kg8 43.Rg3+ Kh8 44.Bg7+ Kg8 45.Bxf8+ Kxf8 46.Qh8+ Kf7 47.Qg8# (or 47.Rg7#).

A.2) 41... Qf7 42.Bh6+ Kg8 43.Rg3+ wins.

A.3) 41... Nxe4 42.Rxc7 Bb7 43.Bh6+ Kg8 (43... Kh7 44.Bf8+; 43... Kh8 44.Rc8+ as in this line) 44.Qg6+ Kh8 45.Rc8+ Bxc8 46.Rxc8+ Nf8 47.Rxf8+ Qxf8 48.Bxf8 and mate soon.

B) 40... Kg8 41.Nf5

B.1) 41... Qf8 42.Qg4+

B.1.a) 42... Kf7 43.Qh5+ Kg8 44.Qg6+ Kh8 45.Bh6 with a winning attack.

B.1.b) 42... Kh7(8) 43.Qh5+ Kg8 44.Qg6+ transposes to B.2.a.

B.2) 41... Qh7 42.Nd6 (42.Qg4+ Kh8 43.Bh6 Nb8 looks unclear) and White, with already three pawns for the bishop, seems to win more material.

B.3) 41... Qe8 42.Qg4+ is crushing.

C) 40... Nf8 41.Qh5+

C.1) 41... Kxg7 42.Bh6+ transposes to A.1.

C.2) 41... Ng6 42.Bxc5 (42.Qh7 Nf8 43.Qh5+ repeats moves) dxc5 43.Rg3 looks winning.

C.3) 41... Kg8 42.Bh6 followed by Rg3 looks very bad for Black.

Well, its not so different from my 40 Qh5+ and 41 Nxg7 from which I'd rather concluded that the WN is poison. So is there a defense for B after the immediate Nxg7? No doubt someone's Fritz or Rybka can tell us. thinkin again, playing Nxg7 immediately gains a tempo for W if BK doesnt recapture, as f7 is not immdiately free for the BQ.

<Jim and others> I wondered about 40 Nxc7, but W was already so far behind in material it seemed a waste to give up such a strongly posted N. Perhaps I should look at it again.

40.Nxg7

A) 40... Kxg7 41.Qh5 Nxe4 (to guard g3) 42.Bh6+ Kg8 (Kh7 43.Bf8+) 43.Qg6+ Kh8 44.Rxc7 Bb7 45.Rc8+ wins.

A.1) 41... Nf8 42.Bxc5! (42.Bh6+? Kh8 43.Bxf8+ Qh7) Nh7 43.Bxb4 Rxc3 44.Rxc3 is winning (exchange +2Ps)

A.1.2) 42... dxc5 43.Rg3+ Ng6 44.Qxg6+ forces mate.

A.2) 42... Kh8 43.Rxc7 Bb7 44.Bf8+ Qh7 45.Qxh7+ Kxh7 46.Rxd7+ wins.

B) 40... Nxe4 41.Nf5! Rxc3 (or Nxc3) 42.Qh5+ Kf8 43.Bh6+ wins

C) 40... Rxe4 41.Nf5 followed by Qh5+ is similarly potent.

D) 40... Nf8 41.Nf5 Qd8 43.Qh5+ Kg8 (Ng6 44.Qh7+ forces mate) 44.Bxc5 followed by Rg3+ wins

I don't see any really tough defenses for black, so maybe I'm missing something.

1) 40.Nxc7 looks simple enough, but seeing that black is up two pieces (~6.50 pawns) vs. 2 pawns ( 4.50) and that taking the rook (~5.00 pawns) leaves white at 0.50 pawns ahead and after 40...Nxe4 black may be ahead by 0.50 pawns. So this suggests 40.Nxc7 is likely not the best move.

2) Black threatens the simple 40...Nxe6 (trading when ahead).

I didn't consider 40.Nxg7 at this point since that move seems counter-intuitive (trading when behind). First I considered checks and only one seemed very feasible (40.Qh5+).

Black has only one response which makes the move especially forcing, 40...Kg8.

Then I considered 41.Nxg7, since 41...Kxg7 42.Bh6+ Kh8 43.Rg3 looks horrifying. On 41...Qxg7, 42.Bh6 followed by 43.Rg3 looks strong.

I then sampled a few other moves, 40.Qg4 and 40.Nxg7, trying to avoid the mistake I made yesterday.

40.Qg4 quickly looks bad after 40...Nxe6 which makes Qg4 look silly.

40.Nxg7 looked interesting since 40...Kxg7 41.Qh5 threatening 42.Bh6+ and 43.Rg3. If 41...Nxe4, 42.Rxc7 looks very good.

So it's a toss-up between 40.Nxg7 and 40.Qh5+. I didn't see a defense to either one so I couldn't make up my mind which was better.

If 40...Nxe4, then 41 Rc6 wins at least the a pawn. In fact, if black follows with 41...Bb7, then 42 Qg4!, below, with the threat 43 Ne6 follows.

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If black takes the rook with 42...Bxc6, then 43 dxc6 double attacks the knight and creates a powerful passed pawn.

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