Trick question? You decide!
Posted: Thu Oct 09, 2008 12:09 pm
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 gWhich 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:
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,
By the way, to make 'part g' true, it would have to be
A intersect {1} = {1}
or
A intersect {{1}} = {{1}}
/rant
And on problem 1, part g
Code: Select all
A = {1, {1}, {2}}*
Is "A intersect {{1}} = {1}**" true?
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)
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,
Code: Select all
Given A = {1, {2}, {3}}, is A intersect {1, {2}, 99} = 1, {2}?
(false, {1, {2}})
A intersect {1} = {1}
or
A intersect {{1}} = {{1}}
/rant