@article{Hammond2003Ladder,
  author =   {Tracy Hammond and Randall Davis},
  title =    {{LADDER}: A Language to Describe Drawing, Display,
                  and Editing in Sketch Recognition},
  year =     {2003},
  journal =  {Proceedings of the 2003 Internaltional Joint
                  Conference on Artificial Intelligence (IJCAI)},
  address =  {Acapulco, Mexico},
  OPTkeywords =  {General Sketch Recognition, Language}
}