COMPETITION! Longest move to mate?

[drahacikfm]

In problem 69610 if you play 1...Qe2 (not the best move) you then have a Mate in 77!  That must be a record.

Let's have a competition and see if anyone can find a position in the endgame problems with a longer mate!

Actually I mean a move in the Legal Move List with a longer mate.  I don't think any of the endgame problems themselves are mate in 77 or more.

[lardingd]

Couldn't resist looking into that Qe2 there >_>. The agonizing effort from there is horrific, but kind of cute.

Interesting that despite a 2 problem limit, you can still explore end game problems based on number.

[richard]

Hi lardingd,

I make the point in the membership page that the viewing may also fall under the 2/day quota, I'd prefer not to, it depends on server load and usage patterns.

Richard.

[kacparov]

When I was playing around with the Nalimov Tablebases (or however it's called  ) and I found a mate in over 250!

[dhingzpe]

When I was playing around with the Nalimov Tablebases (or however it's called  ) and I found a mate in over 250!

Post the position here if you still remember it! I would like to see it.

[lardingd]

hrmm queen and pawn vs queen end games are really annoying >_>. Shortest mate here is in 39. >< http://chesstempo.com/chess-problems/67904

[drahacikfm]

In the Wikipedia article on Tablebases, it says there is a position of two knights versus a pawn that is a forced mate in 115 moves!

The article doesn't say what the record is for 5-piece endgames, but that might be it.

[kacparov]

And it says that the record is over 300 moves for 6 pieces.
With my over 250 I was close 

[oded ross]

http://kirill-kryukov.com/chess/longest-checkmates/longest-checkmates-sorted-by-length.shtml
All these are distance to mate (DTM), not to conversion to an easier winning endgame (DTC). Some of the shorter "longest mates" are really funny, even if not really relevant to the subject material. One might wonder, for example, when do two queens and a rook take 32 moves to mate a long knight.

Longest forced mates/conversions:

3 Pieces:

• KP-K, 28 moves DTM, 19 moves DTC.

4 Pieces:

• KR-KN, 40 moves DTM [27 moves DTC].
  KBN-K, 33 moves DTC&M
  KQ-KR, 31 moves DTC (that is, capturing the rook)
  KQ-KP, 27 moves DTC

5 Pieces:

• KPP-KP, 127 moves DTM (turning into a KQP-KQ win in 122).
  KQP-KQ, 124 moves DTM, 114 moves DTC.
  KNN-KP, 115 moves DTM, 114 moves DTC, 82 moves DTZ (distance to zeroing - meaning an irreversible move, one that puts the OTB 50-move count back to zero; in this case a pawn move).
  Other maximal wins of over 50 moves include (highlighted are the two most practical by far):
  KQ-KRP, 79 moves DTC; KBN-KN, 76 moves DTC; KQ-KBB, 71 moves DTC; KBB-KN, 66 moves DTC; KQ-KNN, 63 moves DTC; KRB-KB, 62 moves DTC; KQR-KQ, 60 moves DTC; KRP-KR, 60 moves DTC; KRB-KR, 59 moves DTC.

6 Pieces:

• KRN-KNN, 262 moves DTM, 243 moves DTC.
  KRRP-KQ, 253 moves DTM.
  (KRP-KNN and KRN-KNP of 253 and 252 moves DTM respectively are essentially of the record endgame type, with a N promotion on move 1 in both cases. Other 200+ setups also turn quickly into the one of the two above following promotions.)
  KRB-KNN, 238 moves DTM, 223 moves DTC.
  KRN-KBN, 209 moves DTM, 190 moves DTC.
  KQPP-KQ, 182 moves DTM.
  KBBP-KR, 180 moves DTM.
  KQN-KRR, 174 moves DTM, 153 moves DTC.

7 Pieces:

• KQN-KRBN, 517 moves DTC [+8 to mate] (Entry No.316)
  KQBN-KQB (opp. color B), 330 moves DTC (Entry No.311)
  KQBN-KQN, 317 moves DTC [+33 to mate] (Entry No.311)
  KRRN-KRR, 290 moves DTC [+8 to mate] (Entry No.298)

Notes: a longer win in another 7-piece endgame may exist; Quickest checkmate has not been calculated for any 7-move endgame, including these, due to memory and storage constraints.

[drahacikfm]

All these are distance to mate (DTM), not to conversion to an easier winning endgame (DTC).
...
KQ-KR, 31 moves DTC (that is, capturing the rook)
KQ-KP, 27 moves DTC
KRP-KR, 60 moves DTC
KRB-KR, 59 moves DTC.

Would be interesting to have the maximum DTM for these so that it's directly comparable to problems here on Chess Tempo.  Only DTC was available for those?

Interesting web page.  It's amazing that in all 3 endgames KQQRKN, KQRRKN, and KRRRKN there is a position which takes 32 moves to mate.  That seems impossible.  Just give up a queen or rook for the knight, and then mate with your other two pieces in 10 moves or less.  Maybe it's very hard to avoid stalemate with so much power on your side.

Edit:  Oh I see, it's kind of a joke position.  I looked at the position it gives for KQQRKN and Black's knight is forking White's King and one of the queens.  When the White King moves, Black takes one queen and checks forking the other queen.  So in two moves it's KRKN.  It's kind of a silly result, White loses his two queens immediately.

If there was a rule that White cannot be in check in the starting position, I bet these 32-move endgames would be 5 moves or less.

[oded ross]

Hence my "not relevant to subject material" remark with the smiley. Similarly, listing the longest 6-piece EGT, I only mentioned unique setups - for example omitting KRRP-KP which is 218 moves DTM because White to move (not in check, btw) can't stop promotion, so in essence it's KRRP-KQ.
As for White being in check in some record positions, they even listed one in which White is in an illegal double check (KRP-KBN [turning into KRN-KBN], wKc4, bBb3, bNa5) - the EGT generators can't prune these out efficiently.

Regarding your question about the common 4-5 piece endgames:

• KQ-KR, 31 moves DTC, 35 moves DTM.
  KQ-KP, 27 moves DTC, 28 moves DTM.
  KRP-KR, 60 moves DTC, 74 moves DTM.
  KRB-KR, 59 moves DTC, 65 moves DTM.

I didn't list the DTM in my previous post because all four are really straightforward after the conversion (capture/promotion).

[drahacikfm]

Interesting.  It's nice to have these numbers so that after we do a particularly hard problem here on Chess Tempo, we can think "that was 20 moves easier than the hardest one"

I looked at the 74-move KRPKR problem, and played through the best moves using tablebases... amazing problem, the pawn starts on the second rank, and at several points the obvious move such as cutting off the opponent's king on a far-away file doesn't work.

I have a hard time solving the KRBKR problems here that are only mate in 20 or so.  I would hate to see that 65-move problem.

[drahacikfm]

New record for problems here on Chess Tempo:  In problem 67789 if you play 1.Qe1 (not the best move) you then have a mate in 86!

Anyone seen more?

[uri blass]

yes

if you play in practice mode in the same problem
1.Qe1 Rb6+ 2.Kf7 Rb7+ 3.Kg8 Rb8+ 4.Kh7 then you have mate in 89 to find.

[jdcannon]

Endgame table bases kind of scare me.... each time they expand them they are one piece closer to solving chess with a computer which is something i never want to see. I prefer that human solve chess independant of computer aid and if that is never possible... all the better.