Completeness of a Visual Computation Model

Visual programming is the specification of computational processes using diagrams and icons. Traditional computation models such as Turing machines and lambda-calculus, which are based on one-dimensional text strings, are not suitable for visual programming languages. We propose a two-dimensional computation model that requires no text. We also prove that the model is computationallhy complete, i.e., that the model has the same computational power as Turing machines.