Natural Language Processing · 免费预览

上下文无关文法与成分结构

成分（词作为单位）、上下文无关规则与推导、作为隐式语法的树库，以及结构歧义。

1. Context-Free Grammars and Constituency

Context-Free Grammars and Constituency

2. One sentence, many trees

One sentence, many trees

3. Enumerating parses and extracting rules

Enumerating parses and extracting rules

4. Testing for a constituent

Why does the substitution test, replacing a string with a single word of the same category, evidence constituency?

5. The four parts of a grammar

Which of these is NOT one of the four components of a context-free grammar as formally defined?

6. Rewriting from S to a sentence

Starting from $S$ , apply $S \to NP\ VP$ , then $NP \to Det\ N$ and $VP \to V\ NP$ , then $NP \to Det\ N$ again. How many rule applications does the complete derivation to a pure word string take, before any lexical rules? Answer with the number.

7. Two trees for one string

In 'the skipper docked the boat with the sail', what distinguishes the two parses the miniature grammar licenses?

8. Every internal node is a rule

How does a treebank yield a grammar, and why are treebank grammars flat and wide?

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