If I have two sets: A = {a, b, c, d, e} and B = {a, b, c, d, e, f, g, h}. I need to find the difference of A-B. My answer is an empty set. Can you have an empty set?

Question

If I have two sets: A = {a, b, c, d, e} and B = {a, b, c, d, e, f, g, h}.  I need to find the difference of A-B.  My answer is an empty set.  Can you have an empty set?

alekos · Answer

wouldnt that just be A - B = {f,g,h}

anonymous · Answer

The difference of A-B is all the elements that are in Set A and not in Set B.  That is why I thought it would be {}.

cwrw238 · Answer

you certainly can have an empty set

alekos · Answer

that's right but then the question doesnt really make any sense

alekos · Answer

I would ask for B - A

anonymous · Answer

Isn't the question just asking me to find A-B?

cwrw238 · Answer

I'm not sure about this one to be honest

alekos · Answer

send me a screen shot of the question

cwrw238 · Answer

B - A is definitely {f,g,h}

anonymous · Answer

The next one is to find B-A.  I was thinking that I am on the right track in that A-B would be an empty set and B-A would be {f,g,h}

anonymous · Answer

I was typing that @cwrw238

alekos · Answer

it would be more likely that they are asking for B-A

alekos · Answer

ok then the answer to the 1st question is a zero set

anonymous · Answer

I'm not sure only because my understanding of an empty set is that it can occur with a union or an intersection.  I didn't know it can be an empty set with the difference of two sets.

cwrw238 · Answer

I'd have to check it out but i'm inclined to think {} is correct for A-B

cwrw238 · Answer

yes a difference can give an empty set

anonymous · Answer

Thanks for the help.