A computer architecture uses a PushDown Automaton (PDA) and a Context Free Grammar (CFG) to process data. A PDA engine maintains semantic states that correspond to semantic elements in an input data set. The PDA engine does not have to maintain a new state for each new character in a target search string...http://www.google.com/patents/US20060259508?utm_source=gb-gplus-sharePatent US20060259508 - METHOD AND APPARATUS FOR DETECTING SEMANTIC ELEMENTS USING A PUSH DOWN AUTOMATON
