The use of conceptual models has long been confined to the data analysis stage of software development. In recent years, this has been extended to use them at run-time as well, for, among others, querying large amounts of data. This brings afore the need to have tractable logic-based reconstructions of the conceptual models, i.e., in at most PTIME. We provide such a logic-based reconstruction for most of ORM using the Description Logic language CFDInc∀−, which has several features important for conceptual models, notably n-ary relationships, complex identification constraints, and role subsumption. The encoding captures over 96\% of the constructs used in practice in the set of 33 ORM diagrams analysed. The results are easily transferable to EER and UML Class diagrams, with an even greater coverage
