+ const ex &mapped_lh = f(lh);
+ const ex &mapped_rh = f(rh);
+
+ if (!are_ex_trivially_equal(lh, mapped_lh)
+ || !are_ex_trivially_equal(rh, mapped_rh))
+ return (new relational(mapped_lh, mapped_rh, o))->setflag(status_flags::dynallocated);
+ else
+ return *this;