What's the quickest possible draw?

The 4 move 3-move-repetition draw, and the 10 move stalemate are both well known. I'd like to know what's the quickest possible forced draw without using the 3 move repetition or stalemate rules. You must reach a position in which it's impossible for either player to deliver a checkmate. 

The quickest I've found so far is 17 moves (34). If anyone finds something quicker, (even just 33/34) please post it here.

Mathematically, the fastest way to get there is by ending with a two opposite kings and two opposed bishops on the same set color complex (light-squared or dark-squared). At least 14 captures are necessary on each side. At least one pawn push and one king move on each side seem necessary. I'm certain the solution can't be optimised below move 16. If optimisation there is, only one Black move or a full move can be cut.

I have the feeling cutting it down to 17 moves is the best solution there is, and that the problem is optimized.

Here was my best personal try in half an hour, on my own (19 moves):

• There are 2 pawn moves on each side, which is 0,5 more than your solution (2 non-capture moves)
• The 5th move is spent moving the rooks without capturing anything (1 NCM)
• The 12th move is spent moving the bishops without capturing anything (1 NCM)
• There is one king move on each side which doesn't result in any capture (1 NCM)

Hence this try was insufficient. It has 5 NCMs (10) while yours has 3 NCMs (6).

You have 1,5 NCMs spent on pawn moves. The rest (1,5 NCMs) are 9...Ra2, 14.Nd4 and 15...Nd7.

Yep. I think you're right that this puzzle should be easy to solve, since the tactics for keeping more than 4 pieces require many moves.

I think we should be able to get it down to 16.5 though.

Forgetting about how many moves, I wonder what the maximum amount of pieces we can keep on the board and still force a draw, without using stalemate or 3 move repetition rules. So far, I've only found one with twelve pieces each.

I do not understand that question. Is forcing a draw without stalemate or the 3-moves repetition a repetition anyway in long term? If no player can progress anymore, given the combinations on the board are finite (although gigantic), a repetition will happen at one point.

Are you thinking here of the 50 move rule?

Regardless of the repetition rule it is an automatic draw since it is impossible to checkmate one another. And you can probably dance your kings around until 50 moves.

Find me a position with more than 24 pieces on the board where it's impossible for one to checkmate the other and it isn't stalemate.

There can be a forced draw from the starting position only if the opponent has no forced win from the starting position. It would be of great interest if you have indeed found one for one player.

If it's not actually forced then an immediate agreed draw would be the fastest without invoking the rules you mention. The agreed draw immediately terminates the game, so it's then impossible for either player to deliver a checkmate.

I just found one 16.5 (33)

That's called an agreed draw, even though one can still mate the other even If he makes just the slightest possible mistake. I'm looking for positions where it's impossible to play mate even if one player tries his hardest to get mated.

'Great interest?!' I take it you're at least 4,000 Elo.

Yes, I see now what you mean by forced. Forced after the position is reached rather than before - any sequence of moves to reach it.

FIDE basic rules, dead position required where neither side can force stalemate (so not KNNvK, for example, but KBBBvK is OK so long as it's not stalemate).

Is that correct, or is it just a dead position that's not stalemate? (Still think you need to remove the agreed draw rule, but let it pass.)

Almost right (off by 0 even); click on my name.

3 moves, Nf3, Nf6, three times

Er, don't think so. Might not fit the stipulation.

Congratulations!