Enhancing PIXIE's Tutoring Capabilities

This paper discusses the overall design of the PIXIE Intelligent TutoringSystem, and more specifically a series of recent enhancements. Theoriginal system has been implemented to involve three separar! phases:the offline, or model generation, phase, which is completed !prior to anyinteraction with a student, involves the construction of a set of studentmodels for a give, domain. Considerable effort has been expended toensure that these sets are complete and non-redundant. The onlinephase involves the tutorial interaction with a student, consisting ofboth diagnosis and remediation of errors. During the post-interactionanalysis phase, undiagnosed errors are examined and, if consistent,added to the existing domain knowledge base. Four recent enhancementsto the system are taen discussed, each arising from a shortcomingthat was noted in the system as a result of student trials. Two ofthese additions to the system involve the diagnosis of errors, and twoinvolve the remediation of errors.