If we define a relation R on the set N $$\times$$ N as (a, b) R (c, d) $$ \Leftrightarrow $$ a + d = b + c for all (a, b), (c, d) $$\in$$N $$\times$$ N, then the relation is

Let S be the set of all persons living in Delhi. We say that x, y in S are related if they were born in Delhi on the same day. Which one of the following is correct?

Consider the following in respect of sets A and B.

1. (A $$-$$ B) $$\cup$$ B = A

2. (A $$-$$ B) $$\cup$$ A = A

3. (A $$-$$ B) $$\cap$$ B = $$\phi$$

4. A $$ \subseteq $$ B $$\Rightarrow$$ A $$\cup$$ B = B

Which of the above are correct?

If A, B and C are subsets of a universal set, then which one the following is not correct?

where, A' is the complement of A