Ludwig/sub 2/: decoupling program representations from processing models

Ludwig/sub 2/ is a general purpose visual language featuring a consistent internal representation for graph manipulation, arithmetic expressions, and user interaction, but with differing presentations of these language components in order to enhance readability. It has grown out of the earlier Ludwig language project as the generality of the graph operation approach outlined there has become apparent. This paper discusses Ludwig/sub 2/'s representation, presentations and planned programming environment.