Three friends of mine (Albert, Bert and Charles) married three girls (Daphne, Elaine and Francine) but I didn't know who married whom. I asked a mutual acquaintance about the marriages, and he said:
"Well, work it out. If Albert married Elaine, then Bert married Francine, and vice versa."
I said, "That's not enough; can you give me other hint?"
"Right. Either Bert married Daphne and Charles married Elaine, or neither of these couples happened."
"Still not enough, give me something else."
"Let's see... Charles married Francine if and only if Albert married Daphne."
"You are still not helping. Couldn't you tell me at least one specific couple, any one, so I can work out the other two myself?"
He smiled. "That wouldn't help you."
I thought a little, and I knew the three pairs. Who married whom?
...only outlaws would have in-laws.
(Sorry about that.)
Solution: Albert married Francine, Bert married Elaine, Charles married Daphne:
There are only four possible groupings:
Group 1:
Albert married Daphne
Bert married Elaine
Charles married Francine
Group 2:
Albert married Francine
Bert married Daphne
Charles married Elaine
Group 3:
Albert married Elaine
Bert married Francine
Charles married Daphne
Group 4:
Albert married Francine
Bert married Elaine
Charles married Daphne
Only Group 4 matches another group on every one of the pairings. It matches Group 2 with respect to Albert and Francine, it matches Group 1 with respect to Bert and Elaine, and it matches Group 3 with respect to Charles and Daphne. Hence only if the grouping is Group 4, will the revelation of any one specific pairing do no good.
Edited on July 25, 2005, 3:27 pm
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Posted by Penny
on 2005-07-25 15:22:43 |
If marriage were outlawed.....
