  
  [1X19. Coxeter diagrams and graphs of groups[0X
  
      | [10X CoxeterDiagramComponents(D) [0X Inputs a Coxeter diagram D and returns a list [D_1, ..., D_d] of the maximal connected subgraphs D_i.                                                                                                                                                                                                          | 
      | [10X CoxeterDiagramDegree(D,v) [0X Inputs a Coxeter diagram D and vertex v. It returns the degree of v (i.e. the number of edges incident with v).                                                                                                                                                                                                  | 
      | [10X CoxeterDiagramDisplay(D) [0X [10X CoxeterDiagramDisplay(D,"web browser") [0X Inputs a Coxeter diagram D and displays it as a .gif file. It uses the Mozilla web browser as a default to view the diagram. An alternative browser can be set using a second argument. This function requires Graphviz software.                                        | 
      | [10X CoxeterDiagramFpArtinGroup(D) [0X Inputs a Coxeter diagram D and returns the corresponding finitely presented Artin group.                                                                                                                                                                                                                     | 
      | [10X CoxeterDiagramFpCoxeterGroup(D) [0X Inputs a Coxeter diagram D and returns the corresponding finitely presented Coxeter group.                                                                                                                                                                                                                 | 
      | [10X CoxeterDiagramIsSpherical(D) [0X Inputs a Coxeter diagram D and returns "true" if the associated Coxeter groups is finite, and returns "false" otherwise.                                                                                                                                                                                      | 
      | [10X CoxeterDiagramMatrix(D) [0X Inputs a Coxeter diagram D and returns a matrix representation of it. The matrix is given as a function DiagramMatrix(D)(i,j) where i,j can range over the vertices.                                                                                                                                               | 
      | [10X CoxeterSubDiagram(D,V) [0X Inputs a Coxeter diagram D and a subset V of its vertices. It returns the full sub-diagram of D with vertex set V.                                                                                                                                                                                                  | 
      | [10X CoxeterDiagramVertices(D) [0X Inputs a Coxeter diagram D and returns its set of vertices.                                                                                                                                                                                                                                                      | 
      | [10X EvenSubgroup(G) [0X Inputs a group G and returns a subgroup G^+. The subgroup is that generated by all products xy where x and y range over the generating set for G stored by GAP. The subgroup is probably only meaningful when G is an Artin or Coxeter group.                                                                              | 
      | [10X GraphOfGroupsDisplay(D) [0X [10X GraphOfGroupsDisplay(D,"web browser") [0X Inputs a graph of groups D and displays it as a .gif file. It uses the Mozilla web browser as a default to view the diagram. An alternative browser can be set using a second argument. This function requires Graphviz software.                                          | 
      | [10X GraphOfGroupsTest(D) [0X Inputs an object D and itries to test whether it is a Graph of Groups. However, it DOES NOT test the injectivity of any homomorphisms. It returns true if D passes the test, and false otherwise. Note that there is no function IsHapGraphOfGroups() because no special data type has been created for these graphs. | 
  
