# Last Move?

BigDoggProblem
Posers and Puzzles 03 Sep '05 20:24
1. BigDoggProblem
03 Sep '05 20:24

Last move?
2. BigDoggProblem
03 Sep '05 22:19
Mephisto2 has PM'ed the correct solution.
3. 04 Sep '05 05:53
Originally posted by BigDoggProblem
Mephisto2 has PM'ed the correct solution.
what mephisto thinks he is? a living version of Shedder?
4. XanthosNZ
Cancerous Bus Crash
04 Sep '05 06:09
Originally posted by Jusuh
what mephisto thinks he is? a living version of Shedder?
Engines won't solve retrograde puzzles for you. They require a very logical mind, something I sadly do not possess.
5. 04 Sep '05 08:27
Originally posted by XanthosNZ
Engines won't solve retrograde puzzles for you. They require a very logical mind, something I sadly do not possess.
Perhaps he meant that 'Shedder' (or 'Fitz'ðŸ˜‰ is a retrograde equivalent of the other other one?

To be fair, there was a flaw in my solution logic, as BiggDogproblem has shown to me. Despite that my solution (last black move) was still the correct one. As they say: ex falso sequitur quodlibet ðŸ˜‰
6. XanthosNZ
Cancerous Bus Crash
04 Sep '05 08:57
Well let's have a stab at this.

The last move must have been black as white is in check. It must have been a pawn capture on f3. So the question is did it come from e4 or h4.

As the d, e and f pawns have not moved the g5 must be the h pawn as it cannot have reached there by any other means. That makes the f3 pawn the c pawn. Therefore it must have been exf3+.

That can't be it though, it's too simple.

Notice that black's light squared bishop is actually the promoted a pawn perhaps this is involved in what I'm missing.
7. Suzianne
Misfit Queen
04 Sep '05 10:121 edit
Originally posted by XanthosNZ
Well let's have a stab at this.

The last move must have been black as white is in check. It must have been a pawn capture on f3. So the question is did it come from e4 or h4.

As the d, e and f pawns have not moved the g5 must be the h pawn as it cannot have reached there by any other means. That makes the f3 pawn the c pawn. Therefore it must have b ...[text shortened]... ht squared bishop is actually the promoted a pawn perhaps this is involved in what I'm missing.
The g5 pawn could also be the original g pawn and the g6 pawn could be the h pawn. I agree though, the last move had to be fxg3+ (which is what I assumend you meant). As for what piece or pawn it captured, I have no clue.

And as far as the Black's light-squared bishop goes, it had to be the result of the a pawn reaching the 8th rank... except, as you can see, a1 is a dark square which means it had to promote at b1 via a capture. Now how it got past the bevy of pawns on the b file is beyond me, nor do I have a clue what piece it captured to advance to b1. I suspect that like the last "last move" puzzle in another thread, the bishop was placed there as a red herring. After all, it easily could have switched places with the d7 pawn and that would work as well.
8. Suzianne
Misfit Queen
04 Sep '05 10:18
Although now that I think about it, Black's newly promoted light-squared bishop could not have been promoted at b1, since the bishop could not have gotten out... it had to have been promoted at f1, as incredible as that sounds. Still, it looks like a red herring nevertheless.
9. 04 Sep '05 11:17
Originally posted by Suzianne
Although now that I think about it, Black's newly promoted light-squared bishop could not have been promoted at b1, since the bishop could not have gotten out... it had to have been promoted at f1, as incredible as that sounds. Still, it looks like a red herring nevertheless.
It's not a red herring at all, it lets you work out how many captures Black's a-pawn has made, and also it shows that White didn't take any of Black's pawns.

White is missing 10 bits; Black's a-pawn made 5 captures(then got promoted), the c-pawn 4 captures and the h-pawn 1 capture.

I think we have to name the piece on g3 which got captured...
10. Suzianne
Misfit Queen
04 Sep '05 11:32
Originally posted by drumfish
It's not a red herring at all, it lets you work out how many captures Black's a-pawn has made, and also it shows that White didn't take any of Black's pawns.

White is missing 10 bits; Black's a-pawn made 5 captures(then got promoted), the c-pawn 4 captures and the h-pawn 1 capture.

I think we have to name the piece on g3 which got captured...
Hmmm, too much brain-cell activity for me, especially on a Sat night/Sun morning, hehe...
11. 04 Sep '05 13:08
Using ideas from above:

Blacks pawns have had to make 10 captures, which are the f,g and h pawns together with all the white pieces. The white squared bishop must have been taken by hxg6 (the a and c pawns must have taken all captures on black squares.

White has only taken the bishop (on c8), the knights and queen. As the a and d pawns need to have made three captures they must have been these latter pieces. The pawn promotion to bishop and impossibility of c8 capture meaning it can't have been anything else.

Therefore the f,g and h pawns cannot have left their columns. No other captures, yet no capture can have been made in the h column, so this pawn must have made it all the way to the 8th rank so it can be moved into a capturing position (and piece could potentially have done the job - the knight could have escaped if the h-pawn captured prior to moving the g-pawn.

But however, as the g-pawn can't have moved from its column (no captures available) that must be what was taken.

fxg3+ (or PxP ch.)
12. 04 Sep '05 14:161 edit
I couldn't work out what had happened to the white h-pawn, but you've hit the nail on the head. Although we knew that 7 pieces and 3 pawns had been captured, the key here was realising that the h-pawn was promoted to a piece before it was captured.
Black captured pieces on b6,c5,d4,e3,d6 and e5. That accounts for 6 pieces. There were 2 captures made on the f-file, one was a pawn, on f2 or f4, the other must have been a piece. That's 7 pieces.
Similarly, there were 2 captures on the g-file. White's g-pawn was captured on g5, so it must have been a piece on g3 ie the promoted h-pawn.

But which piece escapes me at the moment... heheh.
13. BigDoggProblem