# Thread: can you help me to solve this problem????

1. ## can you help me to solve this problem????

Determine whether the relation R on the set of all people is reflexive,symmetric,antisymmetric, and/or transitive, where (a,b) belongs to real number if and only if...
a) a is taller than b.
b) a and b were born on the same day.
c)a has the same first name as b.
d) a and b have a commom grandparent.

2. ## Re: can you help me to solve this problem????

b) and c) are symmetric because when the relation is true for one, the reverse is also true
i.e if a born on the same day as b then the reverse: b is born on the same day as a is also true

a) Is anti-symmetric because when the relation is true for 1 the opposite of the reverse of the relation is true.
Height_a > Height_b is true

The reverse is Height_b > Height_a

The opposite of the reverse Height_b < Height_a is true

3. ## Re: can you help me to solve this problem????

For "reflexive" and "transitive", do you know the definitions?

Is "a" taller than "a"? Was "a" born on the same day as "a"? Does "a" have the same name as "a"? Does "a" have a common grandparent with "a"?

If "a" is taller than "b" and "b" is taller than "c" is "a" taller than b"? If "a" was born on the same day as "b" and "b" was born on the same day as "c" was "a" born on the same day as "c"?
You do the last two!

4. ## Re: can you help me to solve this problem????

i failed to understand... what do you want to say?????