combinations

Sep 30, 2009 at 6:22 PM

I don't understand it:

In the last example we have 5 element set. We create all possible combinations,

output is:

        31
A
B
C
D
E
E
A B
A C
A D
A E
B C
B D
B E
C D
C E
D E
D E
A B C
A B D
A B E
A C D
A C E
A D E
B C D
B C E
B D E
C D E
C D E
A B C D
A B C E
A B D E
A C D E
B C D E
B C D E
A B C D E
*/

I think there should be exactly 32 combinations (as 2^5=32).
Some of combinations are duplicated, for example:

B C D E
B C D E

Sep 30, 2009 at 6:24 PM

ok, empty set  is 32nd combination, so number "31" in output is correct, then what about duplications?