1. A method for conceptual analysis of a document, the method comprising: accessing a concept graph that includes a plurality of nodes and edges, each node representing a concept and each edge representing a known relation between two concepts; and computing a relevance of the document to concepts in the concept graph, the computing comprising: receiving a priori information about the document including concepts extracted from the document, wherein the concepts extracted from the document include a subset of the concepts in the concept graph; and combining the a priori information and the concept graph to generate a posteriori information that indicates a likelihood that the document is related to each of the concepts in the concept graph.