SME is an agent based on the Structure-Mapping Theory (Gentner, 1983). It constrains the mapping problem with the empirically validated systematicity principle (Falkenhainer et. al., 1990) which means that high order relational similarities are preferred. SME finds many possible mappings, then evaluates them according to the map rules. Similarity is based on analogy (described above), literal similarity (where both relational and object predicates are mapped), mere-appearance (where primarily only the object descriptions are mapped), and abstraction mapping (where the entities in the base domain are variables rather than objects). These correspond to different match rules that can be used with SME.