1. A device, comprising: a processor; and a tangible storage medium having modules of a disambiguation decoder stored thereon for execution by the processor, the modules including: a candidate concept obtaining module configured to obtain a set of candidate concepts of a surface form in a sequence of surface forms in a plaintext; a first probability determining module configured to determine first probabilities for the candidate concepts, a first probability indicating likelihood that the surface form represents the respective candidate concept; a concept selecting module configured to select one of the candidate concepts for the surface form based on the first probabilities and adjacency of the surface forms in the sequence; and an occurrence probability determining module configured to determine occurrence probabilities for the candidate concepts based on the first probabilities and the adjacency of the surface forms in the sequence, an occurrence probability indicating likelihood that the respective candidate concept is mentioned in the plaintext, wherein the concept selecting module is configured to select one of the candidate concepts for the surface form based on the occurrence probabilities.