साँचापरक अर्थविज्ञान (Frame semantics)

 साँचापरक अर्थविज्ञान (Frame semantics)

‘साँचापरक अर्थविज्ञान’ संज्ञानात्मक अर्थविज्ञान के अंतर्गत आर्थी विश्लेषण और निरूपण की एक महत्वपूर्ण पद्धति है, जिसका विकास चार्ल्स फिल्मोर (Charles J. Fillmore, 1929-2014) द्वारा किया गया है। हम जानते हैं कि आधुनिक पश्चिमी भाषाविज्ञान में ‘कारक व्याकरण’ (Case grammar) के प्रणेता चार्ल्स फिल्मोर हैं। इस क्षेत्र में उनकी कृति ‘The Case for Case’ (1968) को क्रांतिकारी माना गया था। 1960 के दशक में चॉम्स्की के सुप्रसिद्ध ‘रूपांतरक प्रजनक व्याकरण’ (TGG) की प्रतिक्रिया स्वरूप विकसित व्याकरणों में यह एक प्रमुख सिद्धांत है। यद्यपि फिल्मोर में 1960 और 1970 के दशक में इस व्याकरण पर पर्याप्त कार्य किया और इसे निरंतर संशोधित परिवर्धित करते रहे, और वह संशोधन-परिवर्धन इतना गतिक (dynamic) था कि उसे आधार बनाकर आगे काम नहीं किया जा सका और स्वयं फिल्मोर दूसरे व्याकरणों और सिद्धांतों पर कार्य करने लगे। ‘Frame semantics’ उन्हीं सिद्धांतों में से एक है।

क्रिया-संजाल (Verbnet) ‘साँचा-संजाल (Framenet)’ और प्रापबैंक (Propbank)  ‘साँचापरक अर्थविज्ञान’ या साँचापरक विश्लेषण पद्धति को समझने के लिए उपलब्ध डाटाबेस हैं। इनमें किसी भी क्रिया (और उस वर्ग की क्रियाओं) की साँचा संरचना देखी जा सकती है। उदाहरण के लिए क्रिया संजाल से कुछ विवरण और एक साँचा देख सकते हैं-

VerbNet (VN) (Kipper-Schuler 2006) is the largest on-line verb lexicon currently available for English. It is a hierarchical domain-independent, broad-coverage verb lexicon with mappings to other lexical resources such as WordNet (Miller, 1990; Fellbaum, 1998), Xtag (XTAG Research Group, 2001), and FrameNet (Baker et al., 1998). VerbNet is organized into verb classes extending Levin (1993) classes through refinement and addition of subclasses to achieve syntactic and semantic coherence among members of a class. Each verb class in VN is completely described by thematic roles, selectional restrictions on the arguments, and frames consisting of a syntactic description and semantic predicates with a temporal function, in a manner similar to the event decomposition of Moens and Steedman (1988).

Each VN class contains a set of syntactic descriptions, or syntactic frames, depicting the possible surface realizations of the argument structure for constructions such as transitive, intransitive, prepositional phrases, resultatives, and a large set of diathesis alternations. Semantic restrictions (such as animate, human, organization) are used to constrain the types of thematic roles allowed by the arguments, and further restrictions may be imposed to indicate the syntactic nature of the constituent likely to be associated with the thematic role. Syntactic frames may also be constrained in terms of which prepositions are allowed. Each frame is associated with explicit semantic information, expressed as a conjunction of boolean semantic predicates such as `motion,' `contact,' or `cause.' Each semantic predicate is associated with an event variable E that allows predicates to specify when in the event the predicate is true (start(E) for preparatory stage, during(E) for the culmination stage, and end(E) for the consequent stage). Figure 1. shows a complete entry for a frame in VerbNet class Hit-18.1.

Figure 1: Simplified VerbNet entry for Hit-18.1 class

Class Hit-18.1
Roles and Restrictions: Agent[+int_control] Patient[+concrete] Instrument[+concrete]
Members: bang, bash, hit, kick, ...
Frames:
Name	Example	Syntax	Semantics
Basic Transitive	Paula hit the ball	Agent V Patient	cause(Agent, E)manner(during(E), directedmotion, Agent) !contact(during(E), Agent, Patient) manner(end(E),forceful, Agent) contact(end(E), Agent, Patient)

VerbNet has recently been integrated with 57 new classes from Korhonen and Briscoe's (2004) (K&B) proposed extension to Levin's original classification (Kipper et al., 2006). This work has involved associating detailed syntactic-semantic descriptions to the K&B classes, as well as organizing them appropriately into the existing VN taxonomy. An additional set of 53 new classes from Korhonen and Ryant (2005) (K&R) have also been incorporated into VN. The outcome is a freely available resource which constitutes the most comprehensive and versatile Levin-style verb classification for English. After the two extensions VN has now also increased our coverage of PropBank tokens (Palmer et. al., 2005) from 78.45% to 90.86%, making feasible the creation of a substantial training corpus annotated with VN thematic role labels and class membership assignments, to be released in 2007. This will finally enable large-scale experimentation on the utility of syntax-based classes for improving the performance of syntactic parsers and semantic role labelers on new domains.

Integrating the two recent extensions to Levin classes into VerbNet was an important step in order to address a major limitation of Levin's verb classification, namely the fact that verbs taking ADJP, ADVP, predicative, control and sentential complements were not included or addressed in depth in that work. This limitation excludes many verbs that are highly frequent in language. A summary of how this integration affected VN and the result of the extended VN is shown in Table 1. The figures show that our work enriched and expanded VN considerably. The number of first-level classes grew significantly (from 191 to 274), there was also a significant increase in the number of verb senses and lemmas, along with the set of semantic predicates and the syntactic restrictions on sentential complements.

Table 1: Summary of the Lexicon's Extension

	Original VN	Extended VN
First-level classes	191	274
Thematic roles	21	23
Semantic predicates	64	94
Syntactic restrictions (on sentential compl)	3	55
Number of verb senses	4656	5257
Number of lemmas	3445	3769

इसे https://verbs.colorado.edu/~mpalmer/projects/verbnet.html पर (प्राप्ति दिनांक- 10-12-2021) विस्तार से देख सकते हैं।