NAME

       nauty-watercluster2  -  generate  small  digraphs  with  given  underlying  graph  (faster
       alternative to directg)

SYNOPSIS

       watercluster2 [ix] [oy] [S] [T] [B] [C] [m]

DESCRIPTION

              Reads graphs in g6 code or multicode (optional) from stdin and directs them

              ix : the indegree of every vertex may be at most x.

              The default maximum indegree is unlimited.

              oy : the outdegree of every vertex may be at most y.

              The default maximum outdegree is unlimited.

              S : allow that for every pair of vertices x,y at most one of the edges x-->y

              and y-->x may be present. By default both of them may be present in the same graph.

              T : Output directed graphs in T-code. This is a simple ASCII output  format.  Every
              line

              contains one graph. First the number of vertices, then the number of directed edges
              and then the list of directed edges with the start first and the end then. E.g.:  3
              2 0 1 2 1 means 3 vertices, 2 directed edges: 0-->1 and 2-->1

              B  :  Output  the  directed  graphs  in a binary code. Every item of the code is an
              unsigned

              char. The first unsigned char is the  number  nv  of  vertices.  The  vertices  are
              numbered  1..nv Then the list of vertices x for which there is a directed edge 1->x
              follow. This list is ended by a 0. Then  the  list  of  outgoing  neighbours  of  2
              follows  --  again ended with a 0, etc.  The code is complete with the 0 ending the
              list of outgoing neighbours of nv.

              C : Do really construct all the directed graphs in memory, but don't  output  them.
              This is not

              a big difference in case of restricted in- and outdegrees, because all that is done
              extra is that edges  are  directed  instead  of  just  keeping  track  of  in-  and
              out-degrees.  This  option  is  intended  only  for  testing  purposes to test also
              routines that are normally not used when counting. Things that would speed  up  the
              counting  also  in some cases of restricted in- and out-degrees -- like multiplying
              the possibilities of assigning directions to edges that can be assigned  directions
              independent  of  each  other  (depending  on  the  degrees  of  the endvertices and
              overlaps) -- are not included.  In case of not restrictive bounds on  the  in-  and
              out-degree  it  not  really  constructing the graphs can be considerably faster. In
              cases of restricted in- and out-degrees the only difference is that the graph isn't
              modified...  The fact that in case of no output the graph is not modified is mainly
              to save  time  for  the  one  case  of  waterclusters,  where  large  numbers  were
              determined.  If large numbers (without output) for other cases shall be determined,
              one should think about adding the multiplication routines.

              m : read multicode instead of g6 code

       This program uses different labelling routines -- all based on the ideas of

       G. Brinkmann, Generating water clusters and other directed graphs, Journal of Mathematical
       Chemistry 46, 1112--1121 (2009)