- #1

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Let X be {x, y, z}

P(X) is the power set.

For all Y,Z is an element of P(X), Y R Z where The number of elements in Y intersect Z is 1.

So I worked out P(X) to be:

{(null), (x), (y), (z), (x,y), (x,z), (y,z)}

Then I don't get the next line, how can the number of elements of Y intersect Z be 1 if all members of Y and Z are elements of P(X)? Isn't Y = Z?