00:01
Okay, so here we got two sets a and b, which are infinite.
00:07
So infinite sets.
00:12
Now, a, can we find two infinite sets such that their union is equal to 0 -1? well, the answer here is no.
00:28
Because if a is infinite, so if the cardinality of a is equal to infinity, then, since a is a subset of a union b, we must have the cardinality of a union b greater than equal to infinity.
00:48
So, this thing implies that a union b must be different from 01 because the cardinality of 01 is 2.
01:01
Now, case, now b, can we find a and b? that their intersection is 0 1.
01:11
Well, in this case we can.
01:14
So yes, example, we can consider, okay, we can consider a equals, for example, negative infinity 1, and b equals 0.
01:36
Oh actually here we are not going to use real numbers we are going to use integers...