+/** Function object not caring about the numerical coefficients for insertion
+ * into third argument of STL's sort(). Note that this does not define a
+ * strict weak ordering since for any symbol x we have neither 3*x<2*x or
+ * 2*x<3*x. Handle with care! */
+struct expair_rest_is_less : public std::binary_function<expair, expair, bool> {
+ bool operator()(const expair &lh, const expair &rh) const { return (lh.rest.compare(rh.rest)<0); }
+};
+
+struct expair_swap : public std::binary_function<expair, expair, void> {
+ void operator()(expair &lh, expair &rh) const { lh.swap(rh); }
+};
+
+inline void swap(expair & e1, expair & e2)
+{ e1.swap(e2); }
+
+// This makes STL algorithms use the more efficient swap operation for ex objects
+inline void iter_swap(std::vector<expair>::iterator i1, std::vector<expair>::iterator i2)
+{ i1->swap(*i2); }
+