26. Классификация глаголов по б. Левин

1.1 Levin's Verb Sense Inventory

Levin classifies 3,104 English verbs into 191 verb classes, based on diathesis alternations (альтернации). Of the 3,104 verbs she covers, 784 are listed as belonging to more than one class. As a result, a verb sense inventory falls out immediately from her classification. To the extent that her main hypothesis is correct, verbs in each class will share certain meaning components, thus constituting a distinctive verb sense.

Verbs that belong to more than one class are considered ambiguous. There are two different types of ambiguous Levin verbs:

pseudo-ambiguous: verbs whose class membership can be guessed correctly solely on the basis of the subcategorization frame it occurs in. Consider for instance the verb serve, which is a member of four Levin classes: GIVE, FIT, MASQUERADE and FULFILLING. Each of these classes can in turn license one of four distinct syntactic frames.

Example 1.1 GIVE: They can serve our guests a good meal. [NP1-V-NP2-NP3]

Example 1.2 FIT: The airline serves 164 destinations. [NP1-V-NP2]

Example 1.3 MASQUERADE: He served Napoleon as minister of the interior. [NP1-V-NP2-PPas]

Example 1.4 FULFILLING: She served an apprenticeship to a still-life photographer. [NP1-V-NP2-PPto]

Genuinely -ambiguous: verbs for which the frame information does not provide sure-fire cues for class disambiguation. An example is given in Example 2 about the verb call where it occurs in a double object frame, but belongs to the class DUB in Example 2.1 and GET in Example 2.2.

Example 2.1 DUB: He called John a fool. [NP1-V-NP2-NP3]

Example 2.2 GET: He called John a cab. [NP1-V-NP2-NP3]

Earlier research on token-level disambiguation of verbs has generally adopted the verb sense inventory of WordNet. WordNet is an online lexical database of English that currently contains approximately 120,000 sets of noun, verb, adjective, and adverb synonyms, each representing a lexicalized concept. A synset (synonym set) contains, besides all word forms that can refer to, a given concept, a definitional gloss and — in most cases — an example sentence. Words and synsets are organized in a hierarchical structure in which they are interrelated by means of lexical and semantic-conceptual links, respectively. WordNet is designed principally as a semantic network, and contains little syntactic information. Levin's verb sense inventory is different from that of WordNet in several respects. In particular, Levin’s verb sense inventory employs different criteria to make sense distinctions of verbs.

Palmer (2000) argues that computational lexicons should support sense distinctions based on three concrete criteria:

1. different predicate argument structures;

2. different selectional restrictions on verb arguments;

3. co-occurrences (происходившие вместе) with different lexical material, especially prepositions.

Levin's verb sense inventory meets Palmer's requirement for concreteness. It relies mainly on diathesis alternations and syntactic frame patterns as the criterion for discriminating verbs, and applies this criterion with great consistency. However, Levin's verb classification has its own limitations. For example, Levin's verb classification is certainly not intended as an exhaustive description of English verbs, their meanings or their behavior. A different grouping might, for example, have occurred if finer or coarser semantic distinctions were taken into account (Merlo and Stevenson 2001; Dang et al. 1998). As pointed out by Kipper et al. (2000), Levin classes also exhibit inconsistencies, and verbs are listed in multiple classes, some of which have conflicting sets of syntactic frames. Hence, some ambiguities may also arise as a result of accidental errors or inconsistencies, and some ambiguities may be missing due to incomplete entries. Despite its imperfection, Levin's verb classification has been shown to be valuable in aiding various NLP tasks including lexical resource construction (Korhonen 2002), semantic parsing (Shi and Mihalcea 2005), and semantic role labeling (Gildea and Jurafsky 2002).

ДИАТЕЗА (от греч. diathesis 'расположение'), синтаксическая категория предиката, отражающая определенное соответствие между участниками обозначаемой предикатом ситуации («семантическими актантами», выполняющими те или иные семантические роли) и именными членами предложения, заполняющими валентности данного предиката, – «синтаксическими актантами», синтаксические роли которых выражены морфологическими или синтаксическими средствами.

Выбор элементов значений, релевантных для выбора аргументов.

Кричать-орать-шелестеть-шептать

2 источника лексической информации: 1) дает информацию, релевантную для синтаксиса (лексическая информация). Задается предикатным шаблоном – рекурсивно задаваемая структура, которая содержит информацию о количестве и свойствах глагольных аргументов.

2) идиосинкразическая информация, нерелевантная для грамматики, позволяющая отличить глаголы друг от друга (энциклопедическая). Содержится в виде значения специальной семантической переменной, содержащейся в шаблоне - лексической константы