Sigrid Ewert

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While a 2-dimensional grid picture grammar may generate pictures (deened as subsets of the unit square) with arbitrarily small details, only a nite number of them can be made visible as raster images for any given raster. We present an algorithm based on bottom-up tree automata which computes the set of all raster images of the pictures generated by a given(More)
Iterated Function Systems IFSs are among the best-known methods for constructing fractals. The sequence of pictures E0; E 1; E 2; : : : generated by an IFS fX; f1; f 2; : : : ; f t g converges to a unique limit E, which is independent of the choice of starting set E0, but completely determined by the choice of the maps fi. Random context picture grammars(More)
Regular tree grammars and top-down tree transducers are extended by random context sensitivity as known from the areas of string and picture generation. First results regarding the genera-tive power of the resulting devices are presented. In particular, we investigate the path languages of random context tree languages.