The construction of shapes

A shape rule a -> |3 applies to a labelled shape 7 whenever there is a transformation r that makes ot a subshape of 7. In this case, a new labelled shape can be obtained by replacing the occurrence of 7(a) in 7 with r(|3). The algorithm required for this process is developed in this paper. This algorithm determines all possible distinct transformations under which a given shape rule applies to a given labelled shape and the corresponding labelled shapes resulting from such applications. The definitions and notations given for labelled shapes and shape grammars by Stiny (1980) are used