- #51

martinbn

Science Advisor

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Well, the same wiki article has thisI understand that as referring to a single ##y##. That is clearly what is described in the SE link.

Note that the Wikipedia definition of Surjective says “if for every ...” instead of “if for any...”

https://en.m.wikipedia.org/wiki/Surjective_function

Does it refer to a single function or all functions?Anyfunction induces a surjection by restricting its codomain to the image of its domain. Every surjective function has a right inverse, and every function with a right inverse is necessarily a surjection. The composition of surjective functions is always surjective. Any function can be decomposed into a surjection and an injection.