// Given a function in its univariate form, return true if it is APN and false otherwise

function IsAPN(f)
P:=Parent(f);
F<al>:=BaseRing(P);
n:=Degree(F);
for i in [0..2^n-2] do
a:=al^i;
set_b:={}; set_a:={};
for y in F do if not y in set_a then
b:=Evaluate(f,y+a)-Evaluate(f,y);
if b notin set_b then Include(~set_b,b); 
else 
return false; end if;
Include(~set_a,y+a); end if;
end for; end for;
return true; 
end function;