Dependency Parsing评估方法(evaluation metrics)小记

本文部分翻译自文章Dependency parsing外加个人批注以及关于如何在Python中具体实现的小笔记.
Kübler, Sandra, Ryan McDonald, and Joakim Nivre. “Dependency parsing.” Synthesis Lectures on Human Language Technologies 1.1 (2009): 1-127.

评估dependency parser以及其他类型的parser标准化的做法是把他们应用到一个treebank的测试集上,然后比较parser的输出和treebank给出的标注(gold standard annotation found in the treebank). (我读下来觉得这句话是废话 ?)最为常用的评估方法有以下几种:

• Exact match 精准匹配: 计算的是完全正确parse的句子所占总句子的比例. (个人觉得这个算下来都不会高,整个句子全都分对对算法来说略显困难;并且大多数情况下我们还是比较关心单个component的parse性能,所以这个我觉得基本不太可能会用到.)
• Attachment score: 这个主要用在dependency parser上,constituent parser不能直接使用.它计算的是拥有正确的head的单词占总单词的比例.它以来的是dependency trees的single-head property. Attachment score又有以下两种
  • Labeled Attachment score(LAS)
  • Unlabeled Attachment score(UAS)

Penn Treebank Constituent Tags

Clause Level

S - simple declarative clause, i.e. one that is not introduced by a (possible empty) subordinating conjunction or a wh-word and that does not exhibit subject-verb inversion.
SBAR - Clause introduced by a (possibly empty) subordinating conjunction.
SBARQ - Direct question introduced by a wh-word or a wh-phrase. Indirect questions and relative clauses should be bracketed as SBAR, not SBARQ.
SINV - Inverted declarative sentence, i.e. one in which the subject follows the tensed verb or modal.
SQ - Inverted yes/no question, or main clause of a wh-question, following the wh-phrase in SBARQ.

Phrase Level

ADJP - Adjective Phrase.
ADVP - Adverb Phrase.
CONJP - Conjunction Phrase.
FRAG - Fragment.
INTJ - Interjection. Corresponds approximately to the part-of-speech tag UH.
LST - List marker. Includes surrounding punctuation.
NAC - Not a Constituent; used to show the scope of certain prenominal modifiers within an NP.
NP - Noun Phrase.
NX - Used within certain complex NPs to mark the head of the NP. Corresponds very roughly to N-bar level but used quite differently.
PP - Prepositional Phrase.
PRN - Parenthetical.
PRT - Particle. Category for words that should be tagged RP.
QP - Quantifier Phrase (i.e. complex measure/amount phrase); used within NP.
RRC - Reduced Relative Clause.
UCP - Unlike Coordinated Phrase.
VP - Vereb Phrase.
WHADJP - Wh-adjective Phrase. Adjectival phrase containing a wh-adverb, as in how hot.
WHAVP - Wh-adverb Phrase. Introduces a clause with an NP gap. May be null (containing the 0 complementizer) or lexical, containing a wh-adverb such as how or why.
WHNP - Wh-noun Phrase. Introduces a clause with an NP gap. May be null (containing the 0 complementizer) or lexical, containing some wh-word, e.g. who, which book, whose daughter, none of which, or how many leopards.
WHPP - Wh-prepositional Phrase. Prepositional phrase containing a wh-noun phrase (such as of which or by whose authority) that either introduces a PP gap or is contained by a WHNP.
X - Unknown, uncertain, or unbracketable. X is often used for bracketing typos and in bracketing the…the-constructions.

Word level

CC - Coordinating conjunction
CD - Cardinal number
DT - Determiner
EX - Existential there
FW - Foreign word
IN - Preposition or subordinating conjunction
JJ - Adjective
JJR - Adjective, comparative
JJS - Adjective, superlative
LS - List item marker
MD - Modal
NN - Noun, singular or mass
NNS - Noun, plural
NNP - Proper noun, singular
NNPS - Proper noun, plural
PDT - Predeterminer
POS - Possessive ending
PRP - Personal pronoun
PRP$ - Possessive pronoun (prolog version PRP-S)
RB - Adverb
RBR - Adverb, comparative
RBS - Adverb, superlative
RP - Particle
SYM - Symbol
TO - to
UH - Interjection
VB - Verb, base form
VBD - Verb, past tense
VBG - Verb, gerund or present participle
VBN - Verb, past participle
VBP - Verb, non-3rd person singular present
VBZ - Verb, 3rd person singular present
WDT - Wh-determiner
WP - Wh-pronoun
WP$ - Possessive wh-pronoun (prolog version WP-S)
WRB - Wh-adverb