[ononimo]

[ QUOTE ]
Actually that is the rule.

[/ QUOTE ]

Actually, that's NOT the rule ... at least not the one that Denny cited. We're dealing with 2 different rules here.

the rule that applies to the situation cited above is NOT the "show one, show all" rule. it's the rule that states, for a checked or bet and called river:

"1. A player must show all cards in the hand face-up on the table to win any part of the pot." (from Robert's Rules of Poker - The Showdown)

the "show one, show all" rule is completely different and does NOT apply to the situation cited (note the section in bold) -- it applies when a player selectively shows his hole cards to one or some opponents at the table but not others:

"6. Show one, show all. Players are entitled to receive equal access to information about the contents of another player’s hand. After a deal, if cards are shown to another player, every player at the table has a right to see those cards. During a deal, cards that were shown to an active player who might have a further wagering decision on that betting round must immediately be shown to all the other players. If the player who saw the cards is not involved in the deal, or cannot use the information in wagering, the information should be withheld until the betting is over, so it does not affect the normal outcome of the deal. Cards shown to a person who has no more wagering decisions on that betting round, but might use the information on a later betting round, should be shown to the other players at the conclusion of that betting round. If only a portion of the hand has been shown, there is no requirement to show any of the unseen cards. The shown cards are treated as given in the preceding part of this rule. " (also from Robert's Rules of Poker - The Showdown)

Granted, these are live game rules ... if someone can cite different rules for tournaments, corrections are welcome.