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# Shortest-proof-game challenge

• #201

No problem.

And off the record, it doesn't have to be something "really good". In fact, if you look at many of the problems posted here - such as the last one - the poster didn't even have a solution, yet they ended up being fantastic exercises!

• #202

heck I have one that I am waiting to try. it is really good.

• #203

One note - If the poster doesn't have a solution, then they can try it too.

• #204

I would like to add the stipulation that white may still legally castle both ways from the final position.

I hope this position is reachable and that I didn't mess up.

• #205

According to my calculations, the theoretical minimum of moves it would take to reach this position is 42.5 moves (I.E. white's last move is labeled 43).

Surprisingly, after trying it out I managed to do it. So I'll just wait a little while before posting it to see where's the competition at, and whether anyone manages to tie me (or god forbid surpass me, but I don't think that's possible).

• #206

I'll just go ahead and post my solution:

Here is my analyse:

Black needs to make a lot more moves than white to reach the final position. So we don't really care for white moving efficiently, but black must move at maximum efficiency.

Looking at the board we can see that white must have made at least 15 captures, which account for all of black's missing pieces. These captures were made inside the triangle from a7 to a3 to e3. In order to calculate the theoretical minimum number of moves, we need to check the minimum number of moves it takes for each black piece to reach this "capture zone" (save for the king which must get to a8).

When we go through each piece individually, it is quite simple to calculate. But there are a few special cases we must look at. For instance, it would take the b8 knight just one move to get to the triangle (a6 square). It would also take the c8 bishop just one move to get to the triangle, but it relies on the same a6 square. So, between the two pieces you must actually make at least 3 moves total. Also, the pawn on a7 shouldn't move at all, since it is already in the triangle, and the rook on a8 will get to d8 after black castles long (which he should), then it would need just 1 move to get to the triangle as well. Finally, black must promote f7, g7 and h7 pawns. But the pawns cannot promote on h1 square (because the rook must stay there the whole time), or e1 square (because of the king) and cannot go through f2 square, which would put the king in check. The pawns may pass through white's pawns by capturing white's 4 absent minor pieces. As it turns out, all three pawns must promote on g1 and it would take exactly 4 captures to achieve it. Finally, after promoting, it would take at least two more moves to get to the triangle. You can check it out yourself to see that you understand why.

The calculation for each piece goes as follows:

a8 rook - 1

b8 knight - 1

c8 bishop - 2

queen - 1

king - 3

f8 bishop - 1

g8 knight - 3

h8 rook - 2

a7 pawn - 0

b7 pawn -1

c7 pawn - 1

d7 pawn - 2

e7 pawn - 3

f7 pawn - 7

g7 pawn - 7

h7 pawn - 7

Total: 42 moves.

The position must be reached with black to move, which is why it must take 42.5 moves.

• #207

If this is accepted, I will go ahead and post the next position (though don't expect anything exceptional).

• #208

I can't find any flaw in your solution. I don't like how fast paced this is. I think we should try to come up with harder problems, but it's often hard to know how difficult your problem will be until someone else tries to do it.

I have learned a little bit from this one though and have ideas on how to make the next one more difficult.

• #209

I agree, it is hard to come up with challenging and unique positions (although, I think your last position was quite good. I enjoyed it). But, while challenge and innovation is fun, I'm not really afraid of faster paced, so-called easier ones. They contribute to the flow of the thread and participation of more players. If this thread was in the "more puzzles" forum I suspect it would have been even better.

Regarding your ideas for future positions - great. Looking forward to it

Anyway, here's a position I assembled rather quickly. I hope it is not too easy for your taste, I assume it is quite easy, since the game is still young.

• #210
shoopi wrote:

I agree, it is hard to come up with challenging and unique positions (although, I think your last position was quite good. I enjoyed it). But, while challenge and innovation is fun, I'm not really afraid of faster paced, so-called easier ones. They contribute to the flow of the thread and participation of more players. If this thread was in the "more puzzles" forum I suspect it would have been even better.

Regarding your ideas for future positions - great. Looking forward to it

Anyway, here's a position I assembled rather quickly. I hope it is not too easy for your taste, I assume it is quite easy, since the game is still young.

It started in the more-puzzles forum, look at the address.

• #211

I see, I wonder why it was moved then... That thread seems to be more populated and commonly visited than "Fun With Chess" thread.

Maybe if we stopped having fun they would move it back...

• #212

16 moves.

• #213

My solution appears to be as good as yours. I've been trying for a very long to do it in 15, but despite being so close, I just can't get it done. Here's one of my solutions in 16:

Despite it all, I'm still unsure whether it really is impossible. It definitely could be. Either way I gave up, so you should post the next diagram.

Also, I hope we're not the only ones viewing this thread...

• #214

Here's an attempt at reviving this thread.

What is the least amount of moves you can reach this position with? I do not have the solution yet. Comon people!

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