+Interval_t<Real>::infinity ()
+{
+ return HUGE_VAL;
+}
+
+template<>
+string
+Interval_t<Real>::T_to_string (Real r)
+{
+ return ::to_string (r);
+}
+
+template<>
+int
+Interval_t<int>::infinity ()
+{
+ return INT_MAX;
+}
+
+template<>
+string
+Interval_t<int>::T_to_string (int i)