This paper proposes a simple formal model for topic maps called the Q model, which can informally be thought of as RDF triples extended with a fourth element representing the identity of the triple, and a fifth element representing the context. This enables the model to efficiently represent statements about other statements, which is the key to being able to represent topic maps compactly. It also enables the model to make each statement unique in the model. Q can thus be used to efficiently implement combined topic map/RDF engines.