Originally posted by Natural Sciencecall them A,B,C,D from left to right
Man ---) Man ---) Man ---) (Wall) (--- Man
Originally posted by aging blitzerif B and C are different, they can figure it out, but how does A and D determine what they have?
call them A,B,C,D from left to right
either B and C are wearing the same colour, in which case A can tell he is wearing the other colour,
or B and C are wearing different colours, so A says nothing.
B then knows C has a different colour to B,
so B knows what he is wearing the other colour than C is wearing.