I. Introduction
Currently there are several unsolved issues in Computer Aided Assessment (CAA) of mathematics answers. Existing CAA systems for mathematics can evaluate either single answers [2], or an expression against a pre-defined set of forms, (e.g. factored, expanded) [3], [4]. A recent paper [5] discusses a system that evaluates multi-step answers, but this system is designed for MOOCs(Massive Open Online Courses) and hence requires a large number of answers in order to perform well.