{ "paper_id": "P79-1002", "header": { "generated_with": "S2ORC 1.0.0", "date_generated": "2023-01-19T08:11:32.936120Z" }, "title": "TOWARDS A SELF-EXTENDING PARSER", "authors": [ { "first": "Jaime", "middle": [ "G" ], "last": "Carbonell", "suffix": "", "affiliation": { "laboratory": "", "institution": "Carnegie-Mellon University Pittsburgh", "location": { "postCode": "15213", "region": "PA" } }, "email": "" } ], "year": "", "venue": null, "identifiers": {}, "abstract": "This paper discusses an approach to incremental learning in natural language processing. The technique of projecting and integrating semantic constraints to learn word definitions is analyzed as Implemented in the POLITICS system. Extensions and improvements of this technique are developed. The problem of generalizing existing word meanings and understanding metaphorical uses of words Is addressed In terms of semantic constraint Integration.", "pdf_parse": { "paper_id": "P79-1002", "_pdf_hash": "", "abstract": [ { "text": "This paper discusses an approach to incremental learning in natural language processing. The technique of projecting and integrating semantic constraints to learn word definitions is analyzed as Implemented in the POLITICS system. Extensions and improvements of this technique are developed. The problem of generalizing existing word meanings and understanding metaphorical uses of words Is addressed In terms of semantic constraint Integration.", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Abstract", "sec_num": null } ], "body_text": [ { "text": "Natural language analysis, like most other subfields of Artificial Intelligence and Computational Linguistics, suffers from the fact that computer systems are unable to automatically better themselves.", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Introduction", "sec_num": "1." }, { "text": "Automated learning ia considered a very difficult problem, especially when applied to natural language understanding. Consequently, little effort ha8 been focused on this problem. Some pioneering work in Artificial intelligence, such as AM [I] and Winston's learning system 1\"2] strove to learn or discover concept descriptions in well-defined domains. Although their efforts produced interesting Ideas and techniques, these techniques do not fully extend to \u2022 domain as complex as natural language analysis.", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Introduction", "sec_num": "1." }, { "text": "Rather than attempting the formidable task of creating a language learning system, I will discuss techniques for Incrementally Increasing the abilities of a flexible language analyzer. There are many tasks that can be considered \"Incremental language learning\". Initially the learning domain Is restricted to learning the meaning of new words and generalizing existing word definitions. There ere a number of A.I. techniques, and combinations of these techniques capable of exhibiting incremental learning behavior. I first discuss FOULUP and POLITICS, two programs that exhibit a limited capability for Incremental word learning. Secondly, the technique of semantic constraint projection end Integration, as Implemented in POLITICS, Is analyzed in some detail. Finally, I discuss the application of some general learning techniques to the problem of generalizing word definitions end understanding metaphors.", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Introduction", "sec_num": "1." }, { "text": "Learning word definitions In semantically-rich contexts Is perhaps one of the simpler tasks of incremental learning. Initially I confine my discussion to situations where the meaning of a word can be learned from the Immediately surrounding context. Later I relax this criterion to see how global context and multiple examples can help to learn the meaning of unknown words.", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Learning From Script Expectations", "sec_num": "2." }, { "text": "The FOULUP program [3] learned the meaning of some unknown words in the context of applying s script to understand a story. Scripts [4, 5] are frame-like knowledge representations abstracting the important features and causal structure of mundane events. Scripts have general expectations of the actions and objects that will be encountered in processing a story. For Instance, the restaurant script expects to see menus, waitresses, and customers ordering and eating food (at different pre-specifled times In the story).", "cite_spans": [ { "start": 4, "end": 22, "text": "FOULUP program [3]", "ref_id": null }, { "start": 132, "end": 135, "text": "[4,", "ref_id": null }, { "start": 136, "end": 138, "text": "5]", "ref_id": null } ], "ref_spans": [], "eq_spans": [], "section": "Learning From Script Expectations", "sec_num": "2." }, { "text": "FOULUP took advantage of these script expectations to conclude that Items referenced in the story, which were part of expected actions, were Indeed names of objects that the script expected to see. These expectations were used to form definitions of new words. For instance, FOULUP induced the meaning of \"Rabbit\" in, \"A Rabbit veered off the road and struck a tree,\" to be a self-propelled vehicle. The system used information about the automobile accident script to match the unknown word with the script-role \"VEHICLE\", because the script knows that the only objects that veer off roads to smash Into road-side obstructions ere self propelled vehicles.", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Learning From Script Expectations", "sec_num": "2." }, { "text": "The POLITICS system E6, 7] induces the meanings of unknown words by a one*pass syntactic and semantic constraint projection followed by conceptual enrichment from planning and world-knowledge inferences. Consider how POLITICS proceeds when It encounters the unknown word \"MPLA\" In analyzing the sentence: \"Russia sent massive arms shipments to the MPLA In Angola.\"", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Constraint Projection In POLITICS", "sec_num": "3." }, { "text": "Since \"MPLA\" follows the article '*the N it must be a noun, adjective or adverb. After the word \"MPLA\", the preposition \"in\" Is encountered, thus terminating the current prepositional phrase begun with \"to\". Hence, since all well-formed prepositional phrases require a head noun, and the \"to\" phrase has no other noun, \"MPLA\" must be the head noun.", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Constraint Projection In POLITICS", "sec_num": "3." }, { "text": "Thus, by projecting the syntactic constraints necessary for the sentence to be well formed, one learn8 the syntactic category of an unknown word. it Is not always possible to narrow the categorization of a word to a single syntactic category from one example. In such cases, I propose Intersecting the sets of possible syntactic categories from more then one sample use of the unknown word until the Intersection has a single element.", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Constraint Projection In POLITICS", "sec_num": "3." }, { "text": "POLITICS learns the meaning of the unknown word by a similar, but substantially more complex, application of the same principle of projecting constraints from other parts of the sentence and subsequently Integrating these constraints to oonetruot a meaning representation.", "cite_spans": [], "ref_spans": [], "eq_spans": [], "section": "Constraint Projection In POLITICS", "sec_num": "3." }, { "text": "In the example above, POLITICS analyzes the verb \"to send\" as either in ATRANS or s PTRAflS. (Schank [8] J~ERPONe the MPLA) Is s location or an agent. Physical objects, suchas weapons, are PTRANSed to locations but ATRANSed toagents. The conceptual analysis of the sentence, with MPLAas yet unresolved, Is diagrammed below:\u2022[CIPSl <is> LOC vii ~qNGOLAet*SUSSIA* <-~RTRRNS \u2022l mlq.R) d IN, iq[CIPillIIN< ,,ffi/$SIRi,I", "html": null, "type_str": "table", "text": "discusses the Conceptual Dependency case frames. Briefly, a PTRANS IS s physical transfer of location, and an ATRANS Is an abstract transfer of ownership, possession or control.) The reason why POLITICS cannot decide on the type of TRANSfer is that it does not know whether the destination of the transfer (i.e.," }, "TABREF1": { "num": null, "content": "
I POLITICS Pun --2/06/76 !
\u2022 : INTERPRET US-CONSERVRT IVE)
INPUT STORY, Russia sent massive arms ship.eats
to the flPL.A in Re,gels.
PARSING... (UNKNOUN UOROI MPLA)
:SYNTACTIC EXPECTATION! NOUN)
(SERRNTIC EXPECTATION; (FRANC: (ATRONS PTRONS) SLOTI RECIP
REQ, ILOC ROTOR))) COflPLETEO.
CREATING N( u MEMORY ENTRY, *flPLRo
INFERENCE, ~,MPLRo MIAY BE A POLXTICI:n. FACTION OF mARGOt.fiG
|NFEfl(NCE, eflUSSIAe RTRRNS eRRMSo TO tAPLRo
INFERENCE; *MPLAe IS PNOOROLY aCOflMUNXSTe
INFERENCE, GOAL OF aMPLRa IS TO TAK( OVEN eANOOl.Ae
INSTANTIATING SCAIPTJ SRIONF
INFERENCE; GOAL OF eRUSSIAa I$ toNGOLflo TO BE \u00a2comflNl|$Te
I Question-salem-dialog )
441hst does the MPLA ~ent the arms foP?
TNE RPLR MANTa TO TAKE OVER RNGOLR USING THE NEIMONS.
I~he( might the ether factionS in An(iolll de?
THE OTHER FACTIONS NAY ASK SORE OTHER COUNTRY FOR RRflS.
| Reading furthcP Input ]
INPUT STORY; +The Zunqabl faction oleoPatlng fPoe the I~PLA
plateau received the $ovist uealNme.
PARS |NO... CONPLETEO \u2022
GREAT|NO NEW N(NORY ENTRY: aZUNGRO|a
ACTIVE CONTEXT RPPLJCRItLE, ~IONF
C1 ISR CONFLICT, eMPLRe ISR (eFRCTIONo sPI.RTERUe)
(ACTIVATE' (|NFCN(CK C|)) R(OUEST(O
C2 SCRIPT ROLE CONFLICT,
(&R[O-RECXP |N SRIOMF) \u2022 aMPLRe RNO aZUNGABIe
(ACTIVATE (INFCHECK C2)) RE~JEST[O
(INFCHECK C1 C2) INVOKEOt
RTTERPT TO MERGE MEMORY ENTRIES, (*
", "html": null, "type_str": "table", "text": "M~.Ae aZON~Ia)...FAIUJRE' INFER(lICE RULE CHECK(O (RULEJFI . SRIOMF)...OK INFERENCE RUt.E CHECKED (flULEIGO)...CONFLICT! OELETING RESULT OF RULE/GO C2 RESOt.VEDt ~f'~'LRe ]SA *PLRTEIqJe IN eRNGOLRs C2 flESOLVEO; UlAI?-RECIP IN SRIOMF) \u2022 eZONGROIo REDEFINING enPLRe AS eZUNGRe|O...COMPI.IrTEO. CREATING HEM orlPLRo fl(NORY (NTNY...CORPLET(O." } } } }