User directory services, such as a database service cataloging people in a company or community, are important components today to many online applications. Furthermore, the design of computer applications and interfaces that are appropriate to currently marginalized communities, such as those in rural and poor areas of the developing world, has become an increasingly important research area. We have developed and tested a novel user directory service made specifically for rural communities and for users with low written and computer literacy. Our system supports a new interface design that allows users to perform directory searches for people across a number of dimensions without requiring written literacy nor keyboarding skills. This user directory service was tested in a rural community of the Dominican Republic. Initial results suggest that the general user interface and iconography, was effective in supporting users with a range of written literacy and computer skills. However, results show that the Boolean query mechanism, as implemented, is difficult to master.

A new binary code of length ten and minimum Hamming distance four is presented. It contains 40 words and is therefore optimal. It gives rise to a new sphere packing in ten dimensions. Furthermore, it is proved that a binary code of length 11 and minimum distance four cannot contain 80 words.