Yes, but only to the 14th decimal place.

The real test is not pi but /i/. Only those who can solve the puzzle in less than √-1 seconds are admitted to the innermost circle.

(And if you can manage to solve it in both ∏ *and* √-1 seconds, you may fairly call yourself pi-/i/ed.)

A: I'm always positive!>

This is true until the detractors become subtractors and reduce his value to zero.

</i/: "Be rational."

pi: "Get real.">

Same goes for fractions; 3 out of 2 people don't understand them.

---

Entering this puzzle, I was 3/2 on the week and month. As a result, I spent some extra time trying to solve this puzzle. Normally, me trying to solve a mid or late week puzzle is like a circle: pointless. (damn, all these math puns, that ain't good: math puns are the first sine of madness)

I did not get it though. I should've gotten it, as it looks pretty easy. I did come up with moves such as 26.Bxg7 and 26.Bxc5.

<26 Rxc5 Rxc5>
<27 Rc2 Rc8>

Now we just need to exploit the pinned piece one more time and the pin will work...

<28 Qb5! ...>

Sie müssen diese einfachen Muster lernen können sie in Ihre Spiele zu nutzen...

oder

Black threatens Bxd4 and Rxa2.

White can exploit the position of the black queen with 26.Rxc5 Rxc5 27.Rc2 Rc8 28.Qb5:

A) 28... Rxc2 29.Bxa7 Rxa2 30.Bc5 (due to 30... Rc8# and 30... Rxa7)

A.1) 30... Rac2 31.Bd4 + - [Q+B vs 2R+P] (threatens Qd7 and Qxb4; 31... Raa2 32.Qe8#).

A.2) 30... Ra1+ 31.Kf2 doesn't seem to change anything.

B) 28... Rxb5 29.Rxc8+ Kf7 30.Bxa7 Ra5 31.Bc5 Rxa2 32.Bxb4 followed by Rc3 + - [B].

C) 28... R8c7 29.Qe8#.

From the opening position, the move that we really want to play is 26. Rxc5. This would replace the black bishop on c5 (which can't be pinned diagonally) with a black rook (which can). So that leads us to 26. Rxc5 Rxc5:

click for larger view

Now that the black Rc5 is pinned we follow the usual prescription of adding more pressure to the pin. That leads us to 27. Rc2 Rfc8

click for larger view

White attacks c5 for a second time. Black defends it for a second time. Now white wants to be able to attack c5 for a third time.

You see, there is a basic unfairness in chess. All other things being equal, the attacking side can sometimes attack a pinned piece with more pieces than can defend it. This is because the pinned piece can't defend itself. So if material is level, the attacker can find that he has an extra piece.

This doesn't always work - opposite coloured bishops can mess it up - but it often applies.

But white has a problem. He would like to add his queen into the attack, but there's no obvious way to do this. For example, he would like to warp his queen to d6 or capture on b4. Unfortunately these all take time to arrange - time that white doesn't have because black can easily unpin himself with a move like Qa5.

That's when your eye falls on the move 28. Qb5.

click for larger view

If it works it will add an extra attacker to the pinned Rc5. That's the "I want" part of the puzzle. I want to be able to play 28. Qb5.

We might be tempted to reject 28. Qb5 out of hand because it puts two pieces en prise - the white queen and the white rook. That's the "I can't" phase.

If we look a little deeper, we see that white wins material whichever way black captures. If 28...Rxc5 white doesn't play the disastrous 29. Bxa7 Rxc2. Instead he plays the zwischenzug 29. Rxc8+ Kf7 and only then 30. Bxa7

Or the game continuation when black finds himself with 2R vs Q+B, where the white queen and bishop pair will hoover up all the weak black pawns.

The follow-up move 28. Qb5! is available to put pressure on the pinned piece because of the in-between move (a.k.a. zwischenzug or intermezzo) threat 28...Rxb5 29. Rxc8+ Kf7 30. Bxa7 which leaves White a piece up (i.e. extra Bishop).