We use random context picture grammars to generate pictures through successive refinement. At any stage a picture consists of a shape divided into smaller shapes, each containing a variable or terminal. A variable may be rewritten according to a production of the underlying grammar. This entails either dividing the shape containing it into smaller shapes, or substituting a variable or terminal for it. For visualization purposes every terminal is associated with a color, and its shape is filled with that color. We show pictures generated with random context picture grammars, then concentrate on grammars which use forbidding context only and present a shrinking lemma for the corresponding languages. Int. J. Patt. Recogn. Artif. Intell. 1998.12:939-950. Downloaded from www.worldscientific.com by FLINDERS UNIVERSITY LIBRARY on 02/06/15. For personal use only.
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