#142 Crazyhouse Set Start Board does not accept legal positions

[Xin Xin]

Attached game is showing correctly, but if you go to a position after 26.P@f3 which drops ninth pawn on the board for black and
-right-click on board background
-set start board
-click ok
->error

scidb: FEN is invalid
Too many black pieces.

Scidb is now accepting 8 queens/rooks/bishops/knights and 8 pawns of one colour for holdings (hand pieces).

Correct (= reachable from legal moves from standard starting position) would be for one colour:
queens: 8+8+1+1=18
rooks/bishops/knights: 8+8+2+2=20
pawns: 8+8=16
Promoted and unpromoted pieces could (or should?) be counted separately.

It's great that you can enter positions with fewer pieces than the full 32 set! Also, entering positions which have more than the original 32 set would enable storing possibly interesting crazyhouse (fairy) problem positions. I don't know if that would actually be useful enough for anyone, though.

I couldn't test it with r1224, but in earlier versions one could set the promoted mark to empty squares or pieces that don't promote in crazyhouse.

[Xin Xin]

Apologies, my math is incorrect. I thought about pieces on the board. Pawns in hand can be as many as 16 for one colour. Other figures are of course wrong.

[Gregor Cramer]

I've did a correction of the check for Crazyhouse, and I think that this works (note that "pieces" includes the king, and promoted pieces, but not pawns; holding will be count separately, i.e. "pieces", and "pawns" is not containing the holding):

#Pawns + #Promoted <= 16
#Pieces - #Promoted <= 16
#Holding + #Pieces + #Pawns <= 32 (warning if != 32)
#Pawns + #PawnsInHolding + #Promoted <= 16 (warning if != 16)

Realized with [r1226].

[Xin Xin]

Yes, now position with nine black pawns on the board can be setup. But holdings can only have 8 pawns of one colour, when 16 is possible.

[Gregor Cramer]

Yes, holdings can only have 8 pawns, I don't see a way how to have more pawns in holding.

But I think I have to adjust the other holding values. Example: more than 2 Queens in holding (for one player) is not possible, I don't see a way. In this way max. 4 Rooks, 4, Knights, 4 Bishops.

[Xin Xin]

16 pawns in holding, for example: opponent captures all you pawns, then drops them on the board. Then you capture all the pawns.Not very likely, but legally possible. Other values 2/4/4/4 are right, if you only want to allow positions that can be reached from the normal setup (or fewer pieces).

[Gregor Cramer]

I agree, up to 16 pawns in holding are possible.

And I added some more rules:

#MyPawns + #OpponentPromPieces <= 16
#MyQueens - MyPromQueens <= 1
#MyRooks - MyPromRooks <= 2
#MyBishops - MyPromBishops <= 2
#MyKnights - MyPromKnights <= 2

[Gregor Cramer]

I have to correct the previously given rules (#MyQueens does not include promoted queens):

#MyPawns + #OpponentPromPieces <= 16
#MyQueens + #OpponentQueens - MyPromQueens <= 2
#MyRooks + #OpponentRooks - MyPromRooks <= 4
#MyBishops + #OpponentBishops - MyPromBishops <= 4
#MyKnights + #OpponentKnights - MyPromKnights <= 4

[Gregor Cramer]

Sorry, correction in definition: #MyQueens does include promoted queens.

[Gregor Cramer]

The consistency checks has been corrected and refined, realized with [r1233].