- #1
Bipolarity
- 776
- 2
Am a bit confused about the meaning of cardinality. If ## A \subseteq B ##, then is it necessarily the case that ## |A| \leq |B| ##?
I am thinking that since ## A \subseteq B ##, an injection from A to B exists, hence its cardinality cannot be greater than that of B?
But this cannot be correct, since ##\mathbb{Z}## and ##\mathbb{Q}## have the same cardinality?
Where am I wrong?
Thanks!
BiP
I am thinking that since ## A \subseteq B ##, an injection from A to B exists, hence its cardinality cannot be greater than that of B?
But this cannot be correct, since ##\mathbb{Z}## and ##\mathbb{Q}## have the same cardinality?
Where am I wrong?
Thanks!
BiP