symbol is a term. a term or an index which has some paradoxical meanings, in addition to its conventional meaning. symbols are not innovated, they come from human's creative dreams and imaginations and they show unknown things.old men didn't think about their symbols, they lived with them. so we, as interpreters of dreams, should pay attention not only to the symbol by itself, but als...

The set E of strings is said to be definable (strongly definable) if there is a context-free grammar G such that E is the set of all terminal strings generated from the initial symbol (from all non­ terminal symbols) of G. The classification of definable and strongly definable sets in dependence on minimal number of nonterminal symbols needed for their generation is given.

We study the problem of finding the best headdriven parsing strategy for Linear ContextFree Rewriting System productions. A headdriven strategy must begin with a specified righthand-side nonterminal (the head) and add the remaining nonterminals one at a time in any order. We show that it is NP-hard to find the best head-driven strategy in terms of either the time or space complexity of parsing.

This paper introduces at robust interactive method for speech understatnding. The generatlized LR patrsing is enhanced ill this approach. Patrsing proceeds fl'om left to right correcting minor errors. When at very noisy portion is detected, the patrser skips that portion using a .fake nonterminal symbol. The unidentified portion is resolved by re-utterance of thatt portion which is parsed very ...