I am very familiar with the concepts of bijective, surjective and injective maps but I am interested in improvising the definition of bijection in a way I have not seen done before. To be clear I will provide the definitions that I use for surjective, injective and bijective although they are the common and generally accepted definitions.
f:A→B is surjective ⟺ ∀y∈B, ∃x∈A : f(x)=y.
f:A→B is injective ⟺ ∀x,y∈A, f(x)=f(y)⟹x=y
f:A→B is bijective ⟺ (∀y∈B, ∃x∈A : f(x)=y) ∧ (∀x,y∈A, f(x)=f(y)⟹x=y)
You can see that the definition provided for bijection is simply the conjunction of surjective and injection.
My question is, does it suffice to define bijection as such:
f:A→B is bijective ⟺ ∀y∈B, ∃!x∈A : f(x)=y.
Sorry for making a mountain out of a mole hill with this question, the person I usually work with is not here tonight so I have to run my spit ball ideas by you guys! Thanks in advance.
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