1. In a system for processing natural language, a method for intersecting tapes of a first multi-tape automaton (MTA) and a second MTA, with each MTA having a plurality of tapes and a plurality of paths, comprising: (a) computing a cross-product MTA using the first MTA and the second MTA; (b) generating string tuples for paths of the cross-product MTA; (c) for each string tuple generated at (b), evaluating whether the string of a first tape equals the string of a second tape; (d) for each string tuple evaluated at (c) having equal strings at the first and second tapes, retaining the corresponding string tuple in the cross-product MTA; (e) for each string tuple evaluated at (c) having unequal strings at the first and second tapes, restructuring the cross-product MTA to remove the corresponding string tuple; (f) removing redundant strings in the string tuples retained in the cross-product MTA at (d) to produce an output MTA.
11. The method according to claim 1 , wherein (a)-(f) are performed with a single composition of the first MTA and the second MTA that preserves at least one other tape besides one of the first and second tapes of the cross-product MTA without modification.