# HG changeset patch
# User Nathann Cohen <nathann.cohen@gmail.com>
# Date 1361729470 3600
# Node ID 4275ccc067ec713233e3b8ba8e3ae93e9da05da6
# Parent 36125c7114724a6bf93066dd58b2f54560be29af
Stopgap warning in Graph.modular_decomposition
diff git a/sage/graphs/graph.py b/sage/graphs/graph.py
a

b


5399  5399  Returns the modular decomposition of the current graph. 
5400  5400  
5401  5401  Crash course on modular decomposition: 
5402   
 5402  
5403  5403  A module `M` of a graph `G` is a proper subset of its vertices 
5404  5404  such that for all `u \in V(G)M, v,w\in M` the relation `u 
5405  5405  \sim v \Leftrightarrow u \sim w` holds, where `\sim` denotes 
… 
… 

5443  5443  You may also be interested in the survey from Michel Habib and 
5444  5444  Christophe Paul entitled "A survey on Algorithmic aspects of 
5445  5445  modular decomposition" [HabPau10]_. 
5446   
 5446  
5447  5447  OUTPUT: 
5448   
 5448  
5449  5449  A pair of two values (recursively encoding the decomposition) : 
5450   
 5450  
5451  5451  * The type of the current module : 
5452   
 5452  
5453  5453  * ``"Parallel"`` 
5454  5454  * ``"Prime"`` 
5455  5455  * ``"Serie"`` 
5456   
 5456  
5457  5457  * The list of submodules (as list of pairs ``(type, list)``, 
5458  5458  recursively...) or the vertex's name if the module is a 
5459  5459  singleton. 
5460   
 5460  
5461  5461  EXAMPLES: 
5462   
 5462  
5463  5463  The Bull Graph is prime:: 
5464   
 5464  
5465  5465  sage: graphs.BullGraph().modular_decomposition() 
5466  5466  ('Prime', [3, 4, 0, 1, 2]) 
5467   
 5467  
5468  5468  The Petersen Graph too:: 
5469   
 5469  
5470  5470  sage: graphs.PetersenGraph().modular_decomposition() 
5471  5471  ('Prime', [2, 6, 3, 9, 7, 8, 0, 1, 5, 4]) 
5472   
 5472  
5473  5473  This a clique on 5 vertices with 2 pendant edges, though, has a more 
5474  5474  interesting decomposition :: 
5475   
 5475  
5476  5476  sage: g = graphs.CompleteGraph(5) 
5477  5477  sage: g.add_edge(0,5) 
5478  5478  sage: g.add_edge(0,6) 
… 
… 

5481  5481  
5482  5482  ALGORITHM: 
5483  5483  
5484   This function uses a C implementation of a 2step algorithm 
 5484  This function uses a C implementation of a 2step algorithm 
5485  5485  implemented by Fabien de Montgolfier [FMDec]_ : 
5486  5486  
5487  5487  * Computation of a factorizing permutation [HabibViennot1999]_. 
… 
… 

5512  5512  vol 4, number 1, pages 4159, 2010 
5513  5513  http://www.lirmm.fr/~paul/mdsurvey.pdf 
5514  5514  """ 
 5515  from sage.misc.stopgap import stopgap 
 5516  stopgap("Graph.modular_decomposition is known to return wrong results",13744) 
5515  5517  
5516  5518  from sage.graphs.modular_decomposition.modular_decomposition import modular_decomposition 
5517  5519  