- if (level==1)
- return *this;
-
- if (level==-max_recursion_level)
- throw(std::runtime_error("max recursion level reached"));
-
- return (new relational(lh.eval(level-1),rh.eval(level-1),o))->setflag(status_flags::dynallocated);
+ const ex & subsed_lh = lh.subs(ls, lr, no_pattern);
+ const ex & subsed_rh = rh.subs(ls, lr, no_pattern);
+
+ if (!are_ex_trivially_equal(lh, subsed_lh) || !are_ex_trivially_equal(rh, subsed_rh))
+ return relational(subsed_lh, subsed_rh, o).basic::subs(ls, lr, no_pattern);
+ else
+ return basic::subs(ls, lr, no_pattern);