diff --git a/cv4/list-ops.c b/cv4/list-ops.c
new file mode 100644
index 0000000..59bb2a9
--- /dev/null
+++ b/cv4/list-ops.c
@@ -0,0 +1,62 @@
+#include "list_ops.h"
+
+// constructs a new list
+list_t *new_list(size_t length, list_element_t elements[]){
+  return NULL;
+
+}
+
+// append entries to a list and return the new list
+list_t *append_list(list_t *list1, list_t *list2){
+  return NULL;
+
+}
+
+// filter list returning only values that satisfy the filter function
+list_t *filter_list(list_t *list, bool (*filter)(list_element_t)){
+  return NULL;
+
+}
+
+// returns the length of the list
+size_t length_list(list_t *list){
+  return 0;
+
+}
+
+// return a list of elements whose values equal the list value transformed by
+// the mapping function
+list_t *map_list(list_t *list, list_element_t (*map)(list_element_t)){
+  return NULL;
+
+}
+
+// folds (reduces) the given list from the left with a function
+list_element_t foldl_list(list_t *list, list_element_t initial,
+                          list_element_t (*foldl)(list_element_t,
+                                                  list_element_t)){
+  list_element_t res=0;
+  return res;
+
+}
+
+// folds (reduces) the given list from the right with a function
+list_element_t foldr_list(list_t *list, list_element_t initial,
+                          list_element_t (*foldr)(list_element_t,
+                                                  list_element_t)){
+  list_element_t res=0;
+  return res;
+
+}
+
+// reverse the elements of the list
+list_t *reverse_list(list_t *list){
+  return NULL;
+
+}
+
+// destroy the entire list
+// list will be a dangling pointer after calling this method on it
+void delete_list(list_t *list){
+
+} 
diff --git a/cv4/list_ops.c b/cv4/list_ops.c
new file mode 100644
index 0000000..670b8e5
--- /dev/null
+++ b/cv4/list_ops.c
@@ -0,0 +1,61 @@
+#include "list_ops.h"
+
+// comstruct a new list
+
+list_t *new_list(size_t lenght, list_element_t elements[]){
+	return NULL;
+}
+
+// append entries to a new list and return the new list
+
+list_t *append_list(list_t *list1, list_t *list2){
+	return NULL;
+}
+
+//filter list returninf only values that satisfy the filter function
+
+list_t *filter_list(list_t *list, bool (*filter)(list_element_t)){
+	return NULL;
+}
+
+//returns the lenght of the list
+
+size_t lenght_list(list_t *list){
+	return 0;
+}
+
+//return a list of elements whose values equal the list value transformed by
+//the maaping function
+
+list_t *map_list(list_t *list, list_element_t (*map)(list_element_t)){
+	return NULL;
+}
+
+//folds (reduces) the given list from the left with a function
+
+list_element_t foldl_list(list_t *list, list_element_t initial, list_element_t (*foldl)(list_element_t, 
+			list_element_t)){
+	list_element_t res=0;
+	return res;
+}
+
+//folds (reduces) the given list from the right with a function
+
+list_element_t foldr_list(list_t *list, list_element_t initial, list_element_t (*foldr)(list_element_t, 
+			 list_element_t)){
+	list_element_t res=0;
+	return res;
+}
+
+//reverse elements of the list
+
+list_t *reserve_list(list_t *list){
+	return NULL;
+}
+
+//destroy the entire list
+//list will ve a dangling pointer after calling this method on it
+
+void delete_list(list_t list*){
+
+}