Given two relational schemas R(ABC) and S(ABC), let r(R) and s(S) be the relations (relation table or relation instance) corresponding to R and S respectively as the following:

R

A	B	C
a1	b1	c1
a2	b2	c2

S

A	B	C
a1	b1	c1
a3	b3	c3

Please indicate if the following expression is True or False.

1) ; R n S = (R u S) - (( R - S ) u (S - R))

2) ;

Given relation schema R(A,B,C) and S(C,D,E), please indicate if the following expression is True or False.

3) R semi-join S equivalent to S semi-join R