PIECES(N=4)=PIECES[0],
PIECES[i:0..N]=(when (i < 4) put1  -> PIECES[i+1] |
			    when (i < 3) put2  -> PIECES[i+2] |
				when (i > 0) small -> PIECES[i-1] |
				when (i > 1) big   -> PIECES[i-2] ).


V=(put2 -> GRAND | put1 -> PETIT),

PETIT=(small -> collect -> V |
	   put1 -> GRAND |
	   put2 -> GRAND |
),

GRAND=(big -> collect -> GRAND |
	   small -> collect -> small -> collect -> GRAND |
	   put2 -> GRAND |
	   put1 -> PETIT |
	   put1 -> GRAND ),

RECEPTACLE = (vide -> plein -> RECEPTACLE).