Sets in AMPL
ampl: set A default {};
ampl: set B default {};
ampl: display A;
set A := ; # empty
ampl: let A := {1, 3, 5};
ampl: let B := {2, 4, 6};
ampl: display A; display B;
set A := 1 3 5;
set B := 2 4 6;
ampl: let A := A union {6};
ampl: display A;
set A := 1 3 5 6;
ampl: let B := B diff {4};
ampl: display B;
set B := 2 6;
ampl: display A union B;
set A union B := 1 3 5 6 2;
ampl: display A intersection B;
set A inter B := 6;
ampl: display A diff B;
set A diff B := 1 3 5;
ampl: display A symdiff B;
set A symdiff B := 1 3 5 2;
ampl: set C ordered;
ampl: let C := A symdiff B;
ampl: display C;
set C := 1 3 5 2;
ampl: display first(C);
first(C) = 1
ampl: display last(C);
last(C) = 2
ampl: display member(3,C);
member(3, C) = 5