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Definition: function

f is a function : <=>
   f is a binary relation /\ 
   forall x, y0, y1: (<x, y0> in f /\  <x, y1> in f) => y0=y1.

Definition: partial function from A to B

f: A ->partial B : <=>
   f is a function /\ 
   f subset A x B.

Definition: (total) function from A to B

f: A -> B : <=>
   f: A ->partial B /\ 
   forall x in A: exists y in B: <x, y> in f.

Author: Wolfgang Schreiner
Last Modification: October 14, 1999

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