Equation or not?

[EdDereDdE]

In fact you need only to check for
a) presence of "=" and then
b) exclusion of the special cases ">=", "=>", "<=", "=<"

This function is pretty fast, as it removes most "useless" elements on the first step, even if you got a mega long list at first.
Neither explicit, interpreted loops nor sigma, etc. required either

Please be aware of the CAS("") enclosure ...
Note: implicit engine loops (here in the "remove") are always faster than interpreted "for ..." loops, aren't they?

EXPORT getEq(el)
BEGIN
LOCAL eq:="=",ls:="<",gt:=">";
RETURN CAS("
remove((x)→((INSTRING(x,gt))),
remove((x)→((INSTRING(x,ls))),
remove((x)→(0==(INSTRING(x,eq))),el)
))
");
END;