Combinatorial graph creation and navigation for blind people

Blind individuals have been deprived of the use of diagrams as a form of knowledge representation and an aid to problem solving as well as a means of communication. Our focus is on providing them with access to a specific type of diagram – the node-link diagram, also known as a combinatorial graph. Graphs figure prominently in computer science and software engineering as well as chemistry and other fields. Our goal is to provide blind students and professionals with graph representations that approach the computational equivalence of those available to sighted people. A number of applications have been developed specifically and exclusively to give blind users access to graphs, but separate applications are often not equal. We have worked instead to include them in our graph-based application known as ProofChecker which is intended for universal use. In this paper, we provide examples of general diagram accessibility efforts on behalf of blind people, a discussion of important issues in conveying graphs nonvisually, and a review of the work to date in this area. We also describe how ProofChecker has been made accessible to blind users and how these techniques were applied to a commercial graph-based application. Lastly, we propose the development of an universally accessible graph sketching tool. This tool would allow blind and sighted people to work alone or together using the same interface to create and/or examine graphs and use them for design, problem solving, and teaching/learning.