E-marketplace activities initiated by users in general require representing the user requirements and preferences matched with a set of offerings. One issue of these activities is the heterogeneity among them, which asks for semantic consistency maintenance. This paper solves this problem by applying collaborative concept exchange technology and developing a novel RuleXPM approach. This approach transforms XPM reified documents into rule-based RuleXPM documents that are suitable for making cross-domain inference on heterogeneous emarketplace activities, using defeasible reasoning on a newly designed RuleXPM Inference Engine made from a RuleXPM Inference Algorithm.