I'd like to know why, given two sets $X$ and $Y$, there always exists an injection from $X$ to $Y$ or a surjection from $X$ to $Y$. In other words, why we can always compare the cardinality of two sets.
I appreciate any help!
2026-03-29 15:20:11.1774797611
Existence of injection or surjection between two given sets
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