Active structured documents as user interfaces

Mathematicians manipulate complex abstract objects and expect some help from the computer in this task. A number of systems have been developed for that purpose. The early developments focused on methods and algorithms for numerical and symbolic computations, without paying too much attention to the user interface of systems using these algorithms. Other tools have been developed for helping computer users to prepare mathematical documents. This trend is illustrated by the famous T_EX system (Knuth 1984) that most mathematicians use nowadays. Here again, the emphasis was put on the algorithms and on the quality of the result, but the language provided to the user is not very user-friendly, although very powerful.