Let A be the set of all airports in the world and C the set

Let A be the set of all airports in the world, and C the set of all three–letter airport codes. Further, define a function codeOf : A C. For example, codeOf(ReaganNational) = DCA, and codeOf(TorontoPearsonInternational) = YYZ. Is codeOf injective? Surjective? Bijective? Explain.

Solution

injective means one-to-one function.

and surjective means onto function.

Bijective means both one-to-one and onto.

here codeof(Reagan National)=DCA   i,e three-letter.

    and codeOf(TorontoPearsonInternational) = YYZ. this is also three-letter code.

so this is both one-to-one and onto.

       the code is Bijective.