Let S = {1,2....10} Let R be the relation on P(S), the power set of S, defined by: for any X,Y ∈ P(S),
XRY <=> X∩Y=∅
is it true that ∀X∈P(S),∃Y∈P(S) so that (X,Y)∈R?
I dont know what is (X,Y)?
how many sets X∈P(S) are there so that XR{10}? help me on this one please
Hint: $X$ has some elements. What happens if $Y$ has any of them?