Trick question? You decide!

[MarauderIIC]

So I'm going over the practice test... study materials... whatever for my CS 375 class (logic & theory of computing) (pdf warning)

And on problem 1, part g

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A = {1, {1}, {2}}*
Is "A intersect {{1}} = {1}**" true?

Which the answer to is 'false'.
Obviously (/sarcasm) it's because the intersection between a set and a set containing an element that is "a set that contains 1" should be "a set containing 'a set that contains 1' " not "a set that contains 1". Since, IIRC, an intersection returns a set. So yes the point of intersection itself is {1} but say we had A = {1, 2, 3}, then A intersect {1, 2, 99} would be {1, 2}.

Translations:

Click here to see the hidden message (It might contain spoilers)

*A is a set containing the elements: "1", a set containing "1", and a set containing "2"
**the intersection between the set 'A' and a set containing an element that is "a set that contains 1" is a set containing "1"

So, I am not a fan of her question. Why am I not a fan of her question? Because it's not testing what the return of an intersection is. It's testing whether or not you get confused by multiple curly brackets. A better, test-actual-knowledge question, assuming she still wants to keep multiple curly brackets, would be,

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Given A = {1, {2}, {3}}, is A intersect {1, {2}, 99} = 1, {2}?
(false, {1, {2}})

By the way, to make 'part g' true, it would have to be
A intersect {1} = {1}
or
A intersect {{1}} = {{1}}

/rant

[trufun202]

Fuck.

I don't miss college one bit. :P

[sparda]

I tried solving your problems here, but I hit a snag. Does your book (im assuming book, not professor),
mean subset, or proper subset for the symbol ⊂?

I ask because I know books use this symbol with different meaning.

[MarauderIIC]

Subset. Proper subset has same symbol with an underline. Like < and <.