00:01
For this question, you've been given various relations and you've been asked to determine whether when they're defined for the set of positive integers, they're reflexive, symmetric, antisymmetric, transitive or partial order.
00:16
Now first i'll just note that for something to be a partial order it needs to be reflexive, anti -symmetric and transitive.
00:35
So the first one you've highlighted here is 24 so that's x, y are related if x, y is equal to 1 now if we set x equal to y equal to 1 that's in the relation so 1, 1 is in the relation so similarly we can swap the two ones over and that's in relation so it's the second line of written there shows its reflexive and the third line shows its symmetric because it's symmetric it can't be anti -symmetric.
01:57
So to show that it's transitive, set x equal to y equal to z, all equal to 1.
02:11
Then x is related to y and y is related to z and also x is related to z.
02:26
So for 24 it's reflexive, symmetric and transitive.
02:36
Now 27.
02:44
X and y are related.
02:49
If x equals y squared.
03:02
That's not reflexive.
03:04
Because we can take x equal to y both equal to 2 and 2's not equal to 2 squared...