# Chess Construction Challenge #2-Check!

It’s time for round two!

Given that:

• Black has 6 pawns and a king

• White has three pieces of any kind you to deduce the identity of and a king

Construct:

• A legal position in which both sides help to give a legal sequence of 13 mutual checks

Position variations are allowed. To my knowledge, there is really only one way in which this idea can be constructed. I accept alternate answers.

If you have questions, feel free to ask in the comments section below!

Good luck!

• To clarify: W has three pieces of the same kind that we have to identify, or W has three pieces which might all be of different kinds that we have to identify? – Gareth McCaughan Jul 14 '19 at 20:04

My position has a fourteenth check too, but that's probably ok. :-)

[FEN "8/8/8/8/8/4K3/2pppppp/RR4Nk w - -"]

These are the moves:

 1. Nh3+  d1=N+
2. Rxd1+ cxd1=N+
3. Rxd1+ e1=R+
4. Rxe1+ f1=N+
5. Rxf1+ g1=B+
6. Rxg1+ hxg1=B+
7. Nf2+  Bxf2+

And here's the whole solution uploaded to Lichess.

EDIT: Looks like 15 is also doable:

The final check feels like such a waste of a piece though; the first fourteen checks are possible with white having only two pieces and a king:

[FEN "8/8/6Q1/8/5R2/5p2/ppp1p1p1/R3K1k1 w - -"]

 1. Qb6+   f2+
2. Kd2+   b1=N+
3. Qxb1+  axb1=N+
4. Rxb1+  c1=B+
5. Rxc1+  e1=B+
6. Rxe1+  f1=N+
7. Rexf1+ gxf1=N+
8. Rxf1+

Again, here's the Lichess link.

• Incredible! Thank goodness I checked back. I was wasting so much time not considering promotions! Would love to know your thought process? Had you just seen this kind of pattern before? – Parseltongue Jul 14 '19 at 21:35
• +1. But it's probably not the solution intended by the asker, since it doesn't explain the sequence of extra letters in the question. – msh210 Jul 14 '19 at 21:37
• nice. I think you could substitute queens for one or both of the rooks, too. – SteveV Jul 14 '19 at 21:40
• Well, there seemed to be very few options for b to give check, so it seemed obvious that at least some of black's checks had to be promotions. -> maybe they could all be? I then managed to find a couple of ways to do just that, and one of them had an extra check at the end. – Bass Jul 14 '19 at 21:40
• @RewanDemontay TWO more :-) – Bass Jul 14 '19 at 22:20