You are at a wedding reception in Knave City and are talking with someone (a knight, knave or liar) who makes the following statements:

Chris is married to Alice.

Either Alex is married to Coral or Bob is married to Alice but not both.

Either Alex isn't married to Betty or Chris isn't married to Coral but not both.

I am a knight.

The maid of honor (who is a knight) tells you whether the third statement is true or false. From that, you could figure out who is married to whom...

If you are speaking to a Knight. Then...

Chris is married to Alice ... 1st Statement
Alex is married to Coral ... 2nd Statement (As Bob can then not be married to Alice)
... Bob is married to Betty ... 2nd Statement (As Only these 2 are unmarried)

But then the 3rd statement would be incorrect... as Alex isn't married to Betty AND Chris isn't married to Coral...Hence, you are not speaking to a Knight.

If you are speaking to a Liar. Then...

Chris is either married to Betty or Coral ... 1st Statement
Alex is married to Coral AND Bob is married to Alice ... 2nd Statement
... Chris is married to Betty ... 2nd Statement (As Only these 2 are unmarried)

But then the third statement is true... Hence, you cannot be speaking to a Liar.

Therefore, you are speaking to a Knave.

And since the 4th statement is obviously false...
Statements 1 and 3 are correct ... and you wouldn't need the maid of honor...!

Chris is married to Alice
Alex is married to Betty
Bob is married to Coral

But this contradicts the 3rd statement, which has to be true...

What am i missing ??? Or should i have a different approach altogether ???

Posted by Syzygy on 2007-04-03 10:53:01