Set structure in language:
1 - @s array can contain s, @v, or @s
2 - @v array has one v and may contain s, @s
3 - v is a v-class symbol (a relational symbol)
4 - s is a non v-class symbol (all other symbols)
5 - the root idea of a statement is @s
6 - a @v cannot exist without an enclosing @s
{@s1,@s2,@v1,@v2}=>{{@s1,@v1},{@s1,@v2},{@s2,@v1},{@s2,@v2}
@v has a v symbol
@s doesn’t have a v symbol, but may contain s, @s, and @v
Sequence is same as depth {@s,{@s,{@s}}}
But here we can only use @v to represent it because it is the functional partition of difference.
a b c => {a,{b,{c}}}
