diff --git a/sorting_criteria.c b/sorting_criteria.c
index c093e44..3190c88 100644
--- a/sorting_criteria.c
+++ b/sorting_criteria.c
@@ -11,3 +11,25 @@
 */
 
 #include "sorting_criteria.h"
+
+/**
+ * Determines whether or not `fst` is smaller than or equal to `snd` (ascending order).
+ * 
+ * @param fst The value that is supposed being smaller than `snd`.
+ * @param snd The value to compare.
+ * @return True if `fst` is smaller than or equal to `snd`, false otherwise.
+ */
+bool is_in_asc_order(int fst, int snd) {
+    return fst <= snd;
+}
+
+/**
+ * Determines whether or not `fst` is greater than or equal to `snd` (descending order).
+ * 
+ * @param fst The value that is supposed being greater than `snd`.
+ * @param snd The value to compare.
+ * @return True if `fst` is greater than or equal to `snd`, false otherwise.
+ */
+bool is_in_desc_order(int fst, int snd) {
+    return fst >= snd;
+}
diff --git a/sorting_criteria.h b/sorting_criteria.h
index eb1f8ad..ef82848 100644
--- a/sorting_criteria.h
+++ b/sorting_criteria.h
@@ -27,6 +27,7 @@
  * (the values are in order), false otherwise.
  */
 /* Note: Name the pointer type 'criterion_fn' */
+typedef bool (*criterion_fn)(int fst, int snd);
 
 /**
  * Determines whether or not `fst` is smaller than or equal to `snd` (ascending order).
@@ -35,15 +36,15 @@
  * @param snd The value to compare.
  * @return True if the criterion is satisfied, false otherwise.
  */
-bool is_in_asc_order(<params>);
+bool is_in_asc_order(int fst, int snd);
 
 /**
  * Determines whether or not `fst` is larger than or equal to `snd` (descending order).
  * 
- * @param fst The value that is supposed being smaller than `snd`.
+ * @param fst The value that is supposed being greater than `snd`.
  * @param snd The value to compare.
  * @return True if the criterion is satisfied, false otherwise.
  */
-bool is_in_desc_order(i<params>);
+bool is_in_desc_order(int fst, int snd);
 
 #endif
\ No newline at end of file