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Hey guys! What operation is this symbol?

Hey guys. To introduce myself to the forum, I'm a first (going on second) year Computer Science student from Liverpool UK. Just a quick question on a symbol I have come across;

Attachment 24174

I know the union of sets, joins all elements in A and B. As far as I can tell from the description it is the union of all the sets where is an element of . The lines being the cardinality of this set which has been joined (union).

Am I close at all to it's meaning? If so, could you then have a big intersect symbol to intersect the sets produced. There is also an example later with under the big union symbol, is this just a condition for the union operation?

Thanks guys :)

Phil

Re: Hey guys! What operation is this symbol?

Quote:

Originally Posted by

**philleonard** Hey guys. To introduce myself to the forum, I'm a first (going on second) year Computer Science student from Liverpool UK. Just a quick question on a symbol I have come across;

Attachment 24174
I know the union of sets,

joins all elements in A and B. As far as I can tell from the description it is the union of all the sets

where

is an element of

. The lines being the cardinality of this set which has been joined (union).

Am I close at all to it's meaning? If so, could you then have a big intersect symbol to intersect the sets produced. There is also an example later with

under the big union symbol, is this just a condition for the union operation?

You realize that it is very hard to read the image.

The notation stands for the number of elements in at least one of .

It equal to .

Now please tell us what you need explaining.

Re: Hey guys! What operation is this symbol?

Re: Hey guys! What operation is this symbol?

Quote:

Originally Posted by

**philleonard** As far as I can tell from the description it is the union of all the sets

where

is an element of

. The lines being the cardinality of this set which has been joined (union).

That is correct. The |...| represent the magnitude of that set.

Re: Hey guys! What operation is this symbol?

Click on the image for a larger view please. Thanks for taking time to explain that though.

Edit: Sorry just seen all the new posts too, will read now. Thanks :)

Re: Hey guys! What operation is this symbol?

Thank you so much @**emakarov** :) Fantastic explanation!