# Backwards pawns

Part One: Reach the above position from the starting position

Part Two: Find the fastest way to get to this position.

Answering part one will get you an upvote, answering part two gets the checkmark!

• So for the record, is both colours allowed to be moved? And does both or only one king need to reach the other side? – Adam Mar 13 at 18:28
• @Adam - This is called Retrograde analysis, and the standard constraint is that you are supposed to figure out how the position was arrived at via the normal rules of Chess - that is, alternating white and black moves, with white moving first, no unannounced checks, no failures to escape check, no illegal moves, and so on. – Jeff Zeitlin Mar 13 at 18:50
• Also isn't the term "backwards pawn" a chess term? Lol – North Mar 13 at 19:02
• Yes it is a chess term. – Rewan Demontay Mar 13 at 19:05
• Also, why is my replayer text not showing up? I did the same thing one would do on the chess site and all. I know that is is the same here as well. – Rewan Demontay Mar 13 at 19:12

Update: 28 moves!

Spoilers:

I couldn't solve the issue of wasted moves by W, so I reversed the polarity ;)

And another 29, where W is more efficient but in the end has to wait for B to catch up (W wastes 3 moves waiting).

• I honestly think that this may be the fastest way. It looks too perfect for it be able to be taken any faster. – Rewan Demontay Mar 13 at 23:25
• Great! Each pawn and knight only move twice, each bishop once three rooks twice and one rook once and the black queen only four times. That's as close to optimal as it is likely to get. I certainly can't see any wasted moves there. – Amorydai Mar 14 at 22:12
• @Amorydai Actually I was unhappy with the three useless white Queen moves, and focusing on that I could get half a move better. – Arnaud Mortier Mar 14 at 22:16
• Ah-ha! The improvement keeps coming. – Brandon_J Mar 14 at 22:23
• Perhaps 3 moves shall always be wasted no matter what? – Rewan Demontay Mar 15 at 16:21

UPDATE: I got it down to

32 moves.

There's still some room for improvement, but it's the shortest one so far. Here's the link

• I got it down by half a move using some simple removing in the end. apronus.com/chess/pgnviewer/… – Rewan Demontay Mar 13 at 21:21
• Looking good, looking good! – Brandon_J Mar 14 at 2:06
• My best was 34. I'll wait a while to see if any better answers show up. If not, you have a check-mark coming your way! – Brandon_J Mar 14 at 18:55

Legally:

Illegally:

16 moves if counted normally: 31 moves from standard set-up position into the layout in question (14 pawns to destination + 2 pawns outside, 12 other piece outside + 2 queens to position + 1 king out of check). Which is move each side both pawn except 2 (1 of each side to the outside of the board) and all other pieces except king and queen outside the board.

Credit to @Mukyuu for making the original game. I managed to get it down by half a move.

PGN viewer

So, far, I have been able to get MOST of the pawns in their place. It’s just that the center is so full of pawns that it’s nigh near impossible to switch them. I will look into other ways such as going around the center in some convoluted way.

PGN viewer

UPDATE 1: From what I can tell, the wanted position is actually impossible t get. But you can have a very SIMILAR position, as seen in this game. I will work on getting to be as fast as possible.

PGN viewer

UPDATE 2: I have found an even more similar position whilst finding an even quicker version. This version is faster, yes.

PGN viewer

UPDATE 3: Another attempt, without the annoying spaces in the above game, and only a few moves longer.

PGN viewer

• Yeah I know, this answer is a bit sloppy in organization atm. Is you can edit it to get a working replayer in for both games, please do do that. – Rewan Demontay Mar 13 at 19:16
• apronus.com is not the best choice for SE sites. Try this for putting a replayer in your post. – Brandon_J Mar 13 at 19:42
• I did try that. It didn’t work for some reason. – Rewan Demontay Mar 13 at 19:56
• Yes, I put 4 spaces in front of the FEN and the game record. – Rewan Demontay Mar 13 at 20:53
• @RewanDemontay It was implemented in Chess SE only apparently. – Arnaud Mortier Mar 15 at 8:07