Changeset 1807:5f2f3d982eba in lemon-0.x for lemon/topology.h

Timestamp:

11/16/05 14:26:04 (18 years ago)

Author:

Alpar Juttner

Branch:

default

Phase:

public

Convert:

svn:c9d7d8f5-90d6-0310-b91f-818b3a526b0e/lemon/trunk@2350

Message:

Empty graph is (strongly) connected.

File:

• lemon/topology.h (modified) (5 diffs)

lemon/topology.h

@@ -49 +49 @@
   /// \param graph The undirected graph.
   /// \return %True when there is path between any two nodes in the graph.
-  /// \warning The empty graph is not connected.
+  /// \note By definition, the empty graph is connected.
   template <typename UndirGraph>
   bool connected(const UndirGraph& graph) {
     checkConcept<concept::UndirGraph, UndirGraph>();
     typedef typename UndirGraph::NodeIt NodeIt;
-    if (NodeIt(graph) == INVALID) return false;
+    if (NodeIt(graph) == INVALID) return true;
     Dfs<UndirGraph> dfs(graph);
     dfs.run(NodeIt(graph));
@@ -73 +73 @@
   /// \param graph The graph. It should be undirected.
   /// \return The number of components
+  /// \note By definition, the empty graph consists
+  /// of zero connected components.
   template <typename UndirGraph>
   int countConnectedComponents(const UndirGraph &graph) {
@@ -238 +240 @@
   /// \see connected
   ///
-  /// \warning Empty graph is not strongly connected.
+  /// \note By definition, the empty graph is strongly connected.
   template <typename Graph>
   bool stronglyConnected(const Graph& graph) {
     checkConcept<concept::StaticGraph, Graph>();
-    if (NodeIt(graph) == INVALID) return false;
+    if (NodeIt(graph) == INVALID) return true;
 
     typedef typename Graph::Node Node;
@@ -294 +296 @@
   /// \param graph The graph.
   /// \return The number of components
+  /// \note By definition, the empty graph has zero
+  /// strongly connected components.
   template <typename Graph>
   int countStronglyConnectedComponents(const Graph& graph) {
@@ -357 +361 @@
   ///
   /// \param graph The graph.
-  /// \param compMap A writable node map. The values will be set from 0 to
-  /// the number of the connected components minus one. Each values of the map
-  /// will be set exactly once, the values of a certain component will be
-  /// set continuously.
   /// \retval compMap A writable node map. The values will be set from 0 to
   /// the number of the strongly connected components minus one. Each values