(relation_node): Now unsigned int, not short int.
/* Performing operations on graphs coded as list of adjacency.
If GRAPH is a relation, then GRAPH[Node] is a list of adjacent
/* Performing operations on graphs coded as list of adjacency.
If GRAPH is a relation, then GRAPH[Node] is a list of adjacent
- nodes, ended with -1. */
+ nodes, ended with END_NODE. */
-typedef short int relation_node;
+#define END_NODE ((relation_node) -1)
+
+typedef unsigned int relation_node;
typedef relation_node *relation_nodes;
typedef relation_nodes *relation;
typedef relation_node *relation_nodes;
typedef relation_nodes *relation;