INFORM: An interactive syntax-directed formulae editor

This paper addresses a particular problem in text-processing systems, namely, that of processing mathematical formulae. As in programs in some given programming language, mathematical formulae do not consist of random sequences of characters. Rather, they have some welldefined structure. Therefore, techniques that have been applied successfully in syntax-directed editors for programming languages can also be used in an editor for mathematical formulae. We have built such an interactive syntaxdirected editor for mathematical formulae, called INFORM. It is generated from a grammar that defines the structure and layout of mathematical formulae. Using menu selection and keyboard input, and without knowledge of the underlying text-processing system, INFORM allows the user to create and manipulate a two-dimensional picture of mathematical formulae directly on the screen. In the present paper, the general ideas behind INFORM are discussed.