Maxima Function
setp (a)
Returns true if and only if a is a Maxima set.
setp returns true for unsimplified sets (that is, sets with redundant members)
as well as simplified sets.
setp is equivalent to the Maxima function
setp(a) := not atom(a) and op(a) = 'set.
Examples:
(%i1) simp : false; (%o1) false (%i2) {a, a, a}; (%o2) {a, a, a} (%i3) setp (%); (%o3) true