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Non-empty sets element count (Posted on 2015-04-13) Difficulty: 3 of 5
N is the number of ordered pairs of non-empty sets P and Q that have the following properties:
  1. P Q ={1,2,3,4,5,6,7,8,9,10,11,12}, and:
  2. P Q = Φ, and:
  3. The number of elements of P is not an element of P, and:
  4. The number of elements of Q is not an element of Q
Find N.

No Solution Yet Submitted by K Sengupta    
Rating: 5.0000 (1 votes)

Comments: ( Back to comment list | You must be logged in to post comments.)
re(2): Answer only Comment 5 of 5 |
(In reply to re: Answer only by Daniel)

You are right.

I've solved it too fast, trying a 5-element set, and justifying the

 2^(n-2) answer.

Please see my edited version.



  Posted by Ady TZIDON on 2015-04-13 15:41:50
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