Thread: set and relation

about the relation R={ (n,m)∈ N×N: ∃r ∈ N: n^2 + m^2 = r^2}
N is set of natural number.

a)how to show the converse of R is equal to R?
b)how to prove R is not the empty relation?
c)how to prove R is not a function?

Originally Posted by nyammo

about the relation R={ (n,m)∈ N×N: ∃r ∈ N: n^2 + m^2 = r^2}
a)how to show the converse of R is equal to R?
b)how to prove R is not the empty relation?
c)how to prove R is not a function?

a) You must mean inverse as in .
Note that if then

b) Is it true that

c) Is every term of the first term of some pair in