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NAME

       cant - CAnonicalize N-Triples

DESCRIPTION

       CAnonicalize N-Triples

OPTIONS

       --verbose
              -v      Print what you are doing as you go

       --help -h      Print this message and exit

       --from=uri
              -f uri  Specify an input file (or web resource)

       --diff=uri
              -d uri  Specify a difference file

       Can  have  any  number of --from <file> parameters, in which case files
       are merged. If none are given, /dev/stdin is used.

       If any diff files are  given  then  the  diff  files  are  read  merged
       separately  and  compared with the input files. the result is a list of
       differences instead of the canonicalizd graph. This is  NOT  a  minimal
       diff.  Exits with nonzero system status if graphs do not match.

       This  is  an  independent n-triples cannonicalizer. It uses heuristics,
       and will not terminate on all graphs. It is designed for testing:   the
       output and the reference output are both canonicalized and compared.

       It  uses  the  very  simple  NTriples  format.  It  is  designed  to be
       independent of the SWAP code so that it can be used to  test  the  SWAP
       code. It doesn’t boast any fancy algorithms - just tries to get the job
       done for the small files in the test datasets.

       The algorithm to generate a "signature" for each bnode.  This  is  just
       found  by  looking in its immediate viscinity, treating any local bnode
       as a blank.  Bnodes which have signatures unique within the  graph  can
       be  allocated  cannonical  identifiers as a function of the ordering of
       the signatures. These are then treated as fixed nodes.  If another pass
       is done of the new graph, the signatures are more distinct.

       This  works for well-labelled graphs, and graphs which don’t have large
       areas of interconnected bnodes or large duplicate areas.  A  particular
       failing is complete lack of treatment of symmetry between bnodes.

   References:
              .google       graph       isomorphism      See      also      eg
              http://www.w3.org/2000/10/rdf-tests/rdfcore/utils/ntc/compare.cc
              NTriples: see http://www.w3.org/TR/rdf-testcases/#ntriples

       Not to mention,
              published this month by coincidence:

       Kelly, Brian, [Whitehead Institute]
              "Graph cannonicalization", Dr Dobb’s Journal, May 2003.

              $Id: cant.py,v 1.15 2007/06/26 02:36:15 syosi Exp $

       This  is  or was http://www.w3.org/2000/10/swap/cant.py W3C open source
       licence <http://www.w3.org/Consortium/Legal/copyright-software.html>.

       2004-02-31 Serious bug fixed.  This is a test program, shoul dbe itself
       tested.

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