3 3 votes How many maps $\emptyset:\mathbb{N}\cup \left\{0\right\}\rightarrow \mathbb{N} \cup \left\{0\right\}$ are there, with the property that $\emptyset(ab)=\emptyset(a)+\emptyset(b)$, for all $a, b \in \mathbb{N} \cup \left\{0\right\}$? None Finitely many Countably many Uncountably many Set Theory & Algebra tifrmaths2014 set-theory&algebra functions + – Misbah Ghaya 509 views answer comment Share Follow Print 0 reply Please log in or register to add a comment.