::That's one point from above where I disagree with you Rick. "...is that knowing specifically which shell is lifted up (or specifically which door the host opens) is not the same as knowing that one of two shells (or two doors) must be a loser." In the symmetrical problem there are various sources that say they are the same. Or, they leave out the 'obvious' part '...and this simple solution distributes equally over all contestant door selections and host reveal pairings'. There's nothing to clear up.