1. A method, comprising: digitally sampling an analog waveform voice signal by a processor; examining, via the processor, a tagged input text string based on the digitally sampled analog waveform voice signal for at least one set of substitutions based on content of the input text string; and if the input text string is a substring of a previously tagged input text string and the input text string and at least one additional input text string share a common pre-assigned tag identifier stored in a memory location, eliminating at least one of the input text string and the at least one additional input text string from a natural language grammar.