Relations:
in my book, it says that a relation is a subset of the set of ordered pairs of real numbers, XY. What do they mean by that?

Question

Relations: 
in my book, it says that a relation is a subset of the set of ordered pairs of real numbers, XY. What do they mean by that?

anonymous · Answer

Well, simply put, in set theory a relation is any set which contains some ordered pairs.

anonymous · Answer

It's much easier to think of it graphically.  For the universal set R2, a subset of ordered pairs G is a relation.  The relation xGy is a set which contains all coordinate pairs (x, y) which satisfy G (ex. x^2 + y^2 = 1 - all the points along a circle).

experimentx · Answer

do you know about Cartesian product? http://en.wikipedia.org/wiki/Cartesian_product

anonymous · Answer

What does that have to do with this?

anonymous · Answer

@jim_thompson5910  yes, I know what they mean by a set of ordered pairs of real numbers eg. $$\left \{ (1,2) (3,4)(-6,8) \right \}$$

anonymous · Answer

with spaces in between of course

experimentx · Answer

hmm ... you missed comma between two elements

anonymous · Answer

@bronzegoddess did u get what I said earlier?

anonymous · Answer

thats why said with spaces in between

anonymous · Answer

@vf321  i didn't understand your graphical explanation

experimentx · Answer

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