7/19/2018 - Safe Squares

Isn't 1. ... Qe8+ suboptimal for Black?

Doesn't 1. ... Ke7 allow it to draw by perpetual check with its queen?

No, after 1...Ke7 2.Rxa2 we have a won position for White. Now best for Black is 2...Qg8 and 3.a8=Q is M41 according to the tablebases! More understandable is 2...Qh8+ and it's M27, e.g. 3.Ke4 Qh4+ (or 3...Qa8+ 4.Kf4 Qf8+ 5.Kg3 Qa8 5.h4 and Black can't stop the h-P without sacrificing the Q) 4.Kf5 Qd4 5.a8=Q Qd7+ 6.Kg6 Qd6+ 7.Kh5 Qd1+ 8.Nf3... surprisingly no perpetual check.

Rocky64 wrote:
Isn't 1. ... Qe8+ suboptimal for Black?

Doesn't 1. ... Ke7 allow it to draw by perpetual check with its queen?

No, after 1...Ke7 2.Rxa2 we have a won position for White. Now best for Black is 2...Qg8 and 3.a8=Q is M41 according to the tablebases! More understandable is 2...Qh8+ and it's M27, e.g. 3.Ke4 Qh4+ (or 3...Qa8+ 4.Kf4 Qf8+ 5.Kg3 Qa8 5.h4 and Black can't stop the h-P without sacrificing the Q) 4.Kf5 Qd4 5.a8=Q Qd7+ 6.Kg6 Qd6+ 7.Kh5 Qd1+ 8.Nf3... surprisingly no perpetual check.

Yeah, I realised too late (after I'd already posted) that I was getting suckered by some suboptimal play by Stockfish.

I'm using the Stockfish phone app, which unfortunately doesn't have access to the tablebases.

For instance, here's a game I played as Black and won against Stockfish at level 20. Some positions just seem to confuse the app:

1. Ra5 Qe8+ 2. Kd4? Qd8+ 3. Kc4 Qxa5 4. Ne6+ Ke7 5. Nd4 a1=Q 6. Nc6+ Kd6 7. Nxa5 Qxa5 8. h3 Qxa7 9. h4 Qh7 10. h5 Qxh5 11. Kd3 Ke5 12. Kc4 Qe2+ 13. Kc5 Qc2+ 14. Kb5 Kd5 15. Kb6 Kd6 16. Ka5 Qb3 17. Ka6 Kc6 18. Ka5 Qb5#
0-1

Go figure.

Hmm, the blunder 2.Kd4?? just confirms that Stockfish on Android is pretty hopeless. There's a free app for the 7-piece Lomonosov tablebases (linked at bottom of page) if you're interested.

Rocky64 wrote:

Hmm, the blunder 2.Kd4?? just confirms that Stockfish on Android is pretty hopeless. There's a free app for the 7-piece Lomonosov tablebases (linked at bottom of page) if you're interested.

Um, well actually I'm on the darkside (iPhone) so I guess I'm **** out of luck.

Thanks for that anyway.

No, in that position you do not win with Td8 because it comes Dxd8, Ce6 + - Re7, Cxd8-a1 = d +.

@Manuel76,

Exactly right!!!