# Minimum N moves #2

SwissGambit
Posers and Puzzles 03 Nov '07 07:51
1. SwissGambit
Caninus Interruptus
03 Nov '07 07:51

Minimum number of Knight moves?
2. celticcountry
03 Nov '07 09:56
Five?

Am I missing something here?
3. SwissGambit
Caninus Interruptus
03 Nov '07 17:431 edit
Originally posted by celticcountry
Five?

Am I missing something here?
I'm asking for the minimum number of Knight moves that must have been played to reach this position, not the number of Knight moves White currently has.
4. 03 Nov '07 23:06
First glance it didn't seem to tricky. There can't be any promoted men. Only the f7 pawn has been taken, but that must have been captured there.

White needs 7 captures (2N, 2R, Q, wB and fP)
Black can only make two (R and Q). These must be d7xe6 and axb(not yet sure what.

Looks as though the f1 and f8 bishops must be firstly captured by Ns too, adding to a basic 12 moves for Ns just to reach their final positions if a direct route can be taken.

Problem is that to unblock e6 the B on c8 must be replaced. Only two uncaptures possible for white prior to this, on c6 and d6. Therefore the latter must be the B. It would be easy if two rooks can be uncaptured as I'd want to get both through c8 before the B returns.
5. 04 Nov '07 10:10
15 i think
6. SwissGambit
Caninus Interruptus
04 Nov '07 21:19
Originally posted by gsxr1000
15 i think
Let's see a proof game, or retraction of moves that shows it.
7. 06 Nov '07 21:13

Right, I've retracted back to this position. I'll give the moves a little later, but as white's uncaptures will give black two pieces (R & Q) which are free to waste a move, alongside the wR, the Ns can go about their business.

Both f bishops must be captured upon their starting squares by knights, though in no case do I have to worry about putting the K in check upon approach. And both capturing Ns can move onto their finishing squares without interrupting other crucial play.

Only problem with this is that whites last uncapture (a2xb3) will close his position so must move Ns in order to allow black to retreat the final few moves as quickly as possible.
8. 06 Nov '07 21:251 edit
And conveniently I can make the basic N moves which don't block the position whilst black takes back the final three N moves.

From here white uncaptures to leave a black N on b3, three moves back for each side.

This can be reached as the black c or a pawn can be left on the fourth rank after my retractions (to follow) in the first instance. Plently of opportunity to waste time still available.

Therefore total moves:

bN b8-c6-d4-b3 (3 moves)
bN g8-f6-g4-e3xf1-e3-d5 (6 moves)
wN b1-c3-a4 (2 moves)
wN g1-h3-f4-g6xf8-e6-c7-a8 (7 moves)

Total of 18 moves then.

Edit: I can't go via e6 and c7 as I'd check the K on the way. e6-f5-e6 would solve the problem with two extra moves (to make 20)

It is possible for the N to move from f8 to a4 and the other from b2 to a8 but these both take the same number of moves.

My answer is twenty, not 18.
9. 06 Nov '07 21:47

From here to reach the position in the problem.

1. dxe6 Rg8
2. exf7 Rf8
3. Re6 dxe6
4. Kf1 Bd7
5. Kg1 Bb5
6. Kf1 Bd3
7. cxd3 Rc8
8. Qb3 c4
9. Rd1 c3
10. Ke1 c2
11. Qb4 Rc3
12. bxc3 axb4
13. Ba3 b3
14. Ra1 b2
15. Ra2
10. SwissGambit
Caninus Interruptus
06 Nov '07 22:24
Originally posted by Peakite
And conveniently I can make the basic N moves which don't block the position whilst black takes back the final three N moves.

[fen]r1bqkbnr/pppppppp/8/8/N7/1P5N/1PPPPPPP/R1BQKB1R w KQkq[/fen]
From here white uncaptures to leave a black N on b3, three moves back for each side.

This can be reached as the black c or a pawn can be left on the fourth rank ...[text shortened]... r from b2 to a8 but these both take the same number of moves.

My answer is twenty, not 18.
Correct. Good spot on the Nc7+ issue.
11. 14 Nov '07 13:04
Just 2!
Kc3 and Ka4
The Knight on a8 could be a converted pawn
12. HurricaneConway125
SUPREMO OF SOMERSET
14 Nov '07 16:43
Originally posted by afx
Just 2!
Kc3 and Ka4
The Knight on a8 could be a converted pawn
it clearly isn't seeing as white's A pawn has been doubled onto the B-file so a pawn can't therefore make it to A8
13. sonhouse
Fast and Curious
14 Nov '07 18:14
Originally posted by SwissGambit
[fen]N6k/1p2pPpp/4p3/8/N7/B1PP4/RppPPPPP/4K3[/fen]
Minimum number of Knight moves?
Just out of curiosity, are you ever going to actually play a game? I see you have been here since april and have a grand total of zero games played.
14. SwissGambit
Caninus Interruptus
15 Nov '07 06:04
Originally posted by sonhouse
Just out of curiosity, are you ever going to actually play a game? I see you have been here since april and have a grand total of zero games played.
I've had so many people ask this now that I don't dare ruin the mystique by answering the question.
15. 15 Nov '07 08:18
Originally posted by SwissGambit
I've had so many people ask this now that I don't dare ruin the mystique by answering the question.
Out of curiosity, do you have a fide title?