Top-down parsers make their predictions in pre-order, in which the parent nodes are identified before any of their children, and which imitates leftmost derivations (see Section 6.1); bottom-up parsers perform their reductions in post-order, in which the parent nodes are identified after all of their children have been identified, and which imitates rightmost derivation (see the introduction in Chapter 7). These two orders of producing and visiting trees are called “canonical”, and so are the parsing techniques that follow them.
KeywordsNoun Phrase Parse Tree Input Symbol Active Item Head Spine
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