S = \ {x_ {1}, \ ldots, x_ {n} \} \ subset {\ mathcal {X}}

S = \ {x_ {1}, \ ldots, x_ {n} \} \ subset {\ mathcal {X}}

S = \ {x_ {1}, \ ldots, x_ {n} \} \ subset {\ mathcal {X}}

S = \ {x_ {1}, \ ldots, x_ {n} \} \ subset {\ mathcal {X}}