@Unpublished{DJDHughes:DI,
  author    =  {Hughes, Dominic J.D.},
  title     =  {Deep inference proof theory \emph{equals} categorical proof theory \emph{minus} coherence},
  year      =  {2004},
  note      =  {Unfinished draft, October 6.  http://boole.stanford.edu/\~{\strut}dominic/papers}
}