1. A computer-implemented method of speech recognition, comprising: propagating tokens through a weighted finite state transducer (WFST) having arcs and words or word identifiers as output labels of the WFST, and comprising placing word sequences into a word lattice; generating a word history designation for individual tokens when a word is established at a token propagating along one of the arcs with an output symbol, wherein the word history designation indicates a word sequence; and determining whether or not two or more tokens should be combined to form a single token in a state of the WFST by using, at least in part, the word history designations.