2023/12/23 DPA: "Come Hither Or Go Thither; It Matters Not"

Black to move.

Be aware of that White Bishop lurking on a7, which defends f2.

If Black can get the King to c3, he can play ... Qb4#, as the pawns cut off both light squares.

Aah, and don't forget about Black's sniper on h8...which also contests c3.  That might come in handy.

Material is balanced piece-wise but White has more pawns and, even more significantly, has a passer on c6.

Black's Rook on b8 is en prise.

Oh, and White threatens checkmate with Rxh8+ and Qh7#.

Black can't win material with 1. ... Rxd1+  2. Qxd1 as the Rook on h5 is X-Ray defended by the Queen.

1. Qb4+ is possible but what's the follow-up?

Aah, I think I see it:  1. ... Rxf2+:  sniper Bishop?  Who cares! 

2. Bxf2 [if 2. Ke1/e3 Qe2#] Bc3+  3. Kxc3 [if 3. Ke3 d4#] Qb4#.

Note that, once the Rook moves, the Bishop controls the a1-h8 diagonal.

I've seen this pattern [Queen checkmate with enemy forces blocking opposite color squares; I think it's called a Dovetail.  Here's a blog I wrote about it:

https://www.chess.com/blog/EnPassantFork/common-mating-pattern-backed-into-a-corner

Because of this pattern recognition and recall, I saw the solution fairly quickly [maybe 3 minutes], partially because there were no good looking alternatives and the imminent threat of our own demise.

Key ideas:

• exposed King
• all escape squares are the same color
• one sac whose only purpose is to free up the second sac with no loss of tempo [the Rook sac had to be a check; otherwise, Black gets checkmated]
• Attraction Sacrifice [2. ... Bc3+], which draws the King forward into the mating net

I thought the solution was going to be accepting the Attraction Sac with 3. Kxc3 but it turned out to be the other option of a pawn mate, which is even more elegant.

There were 2 examples of RBBS*:  the White Bishop on a7 and the Black Bishop on h8.  The former turned out to be irrelevant because failing to see it still led to the correct solution but the latter was crucial:  if the solver didn't see it, no solution.

*  "Remote Bishop Blindness Syndrome"

A tendency to miss a Bishop that is somewhat removed from the action, often a White Bishop on a light square or a Black Bishop on a dark square.

Can cause serious miscalculations and material loss.  If you experience these symptoms, hang up immediately and dial up some remote Bishop puzzles.

I anticipate a lot of "bruh, just take the Bishop!  White's playing like my hamster!".  If you're one of them, read the blog entry on the Dovetail above. 

Then again, if you've made it this far in the explanation, it's unlikely you're one of them.