tag in a post to help line up the elements, and added letters below the brackets show the "level" of the brackets.[/QUOTE]
Maybe a simpler way is to use, for example, colors.
S is a set which its members are (the members that are induced in p) AND (the members that are induced in {p} (which is actually p)).
p = { [COLOR="Red"]∅, {∅}, {∅, {{∅}}}[/COLOR] }
{p} = { [COLOR="Blue"]{ ∅, {∅}, {∅, {{∅}}} }[/COLOR] }
In that case
S={ [COLOR="Red"]∅, {∅}, {∅, {{∅}}}[/COLOR] , [COLOR="Blue"]{ ∅, {∅}, {∅, {{∅}}} }[/COLOR] }
or
S={[COLOR="Red"]∅, {∅}[/COLOR], [COLOR="Blue"]{∅, {∅}, {∅, {{∅}}}}[/COLOR], [COLOR="red"]{∅, {{∅}}[/COLOR]}
since order is irrelevant.