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<?xml version="1.0" standalone="yes"?> <Paper uid="P84-1082"> <Title>AUTOMATIC CONSTRUCTION OF DISCOURSE REPRESENTATION STRUCTURES</Title> <Section position="4" start_page="0" end_page="398" type="metho"> <SectionTitle> 2 SyntaJc </SectionTitle> <Paragraph position="0"/> <Section position="1" start_page="0" end_page="0" type="sub_section"> <SectionTitle> 2.1 Syntactic framework and parsing process </SectionTitle> <Paragraph position="0"> The parser used in the Natural Language Analyzer was originally described by Kay (1967) and subsequently implemented in the REL system (Thompson et. al. (1969)). The Natural Language Analyzer uses a modified version of this parser which is due to Bertrand &al (1976, IBM (1981)).</Paragraph> <Paragraph position="1"> Each grammar rule contains the name of an intePpretation routine, and hence each node in the parse tree for a given sentence also contains the name of such a routine. The semantic executer invokes the interpretation routines in the order in which they appear in the parse tree, starting at the root of the tree.</Paragraph> </Section> <Section position="2" start_page="0" end_page="0" type="sub_section"> <SectionTitle> 2.2 Syntactic coverage </SectionTitle> <Paragraph position="0"> The syntactic coverage of the Natural Language Analyzer presently includes</Paragraph> </Section> <Section position="3" start_page="0" end_page="398" type="sub_section"> <SectionTitle> Nouns Verbs </SectionTitle> <Paragraph position="0"> Adjectives and adjectival phrases: gradation, modification by modal adverbial, modification by ordinal number - Units of measure - Noun phrases: definiteness, quantification, interrogative pronouns, personal pronouns, possessive pronouns, relative pronouns - Verb complements: subjects and nominative complements, direct objects, indirect objects, prepositional objects - Noun complements: relative clauses, participial attribute phrases, genitive attributes, appositions, prepositional attributes - Complements of noun and verb: negation, locative adverbials, temporal adverbials - Coordination for nouns, noun phrases, adjectives, verb complexes and sentences - Comparative constructions - Subordinate clauses: conditionals - Sentences : declarative sentences, questions, commands</Paragraph> </Section> <Section position="4" start_page="398" end_page="398" type="sub_section"> <SectionTitle> 2.3 Syntax rules to cover the Kamp fragment </SectionTitle> <Paragraph position="0"> In this section we give the categories and rules used to process the Kamp fragment. The syntax rules given below are somewhat simplified with regard to the full grammars used in the Natural Language Analyzer, but they have been formulated in the same spirit. For a detailed account of the German syntax see Zoeppritz (1984), for the Spanish grammar see Sopefia (1982).</Paragraph> <Paragraph position="1"> Syntactic categories We need the following categories : <NAME>, <NOMEN>, <QU>, <NP> (features: REL, PRO, NOM, ACC), <VERB> (features: TYP=NI, TYP=NA), <SENT>, <SC> (feature: REL).</Paragraph> <Paragraph position="2"> Vocabulary The vocabulary items we have taken from Ramp (1981).</Paragraph> <Paragraph position="3"> <NAME> : Pedro, Chiquita, John, Mary, Bill, ...</Paragraph> <Paragraph position="4"> <NOMEN:/NOM,/ACC> : farmer, donkey, widow, man, woman, ...</Paragraph> <Paragraph position="5"> <VERB:TYP=NI> : thrives, ...</Paragraph> <Paragraph position="6"> <VERB:TYP=NA> : owns, beats, loves, admires, courts, likes, feeds ....</Paragraph> <Paragraph position="7"> <QU> : a, an, every <NP:+PRO,+NOM> : he, she, it <NP:/PRO,+ACC> : him, her, it <NP: /REL,/NOM> : who, which, that <NP:/REL,+ACC> : whom, which, that 2.3.I Syntax rules To help readability, the specification of interpretation routines has been taken out of the left hand side of the syntax rules and has been placed in the succeeding line. The numbers appearing as parameters to interpretation routines refer to the position of the categories on the right hand side of the rules. As can be seen, interpretation routines can be nested where appropriate. The operation of the interpretation routines is explained below.</Paragraph> </Section> </Section> <Section position="5" start_page="398" end_page="399" type="metho"> <SectionTitle> 3 Intermediate Structures </SectionTitle> <Paragraph position="0"> Intermediate Structures are used to facilitate the translation from parse trees to the semantic representation language. They are trees containing all the information necessary to generate adequate expressions in the semantic representation language for the sentences they represent.</Paragraph> <Section position="1" start_page="398" end_page="399" type="sub_section"> <SectionTitle> 3.1 The definition of Intermediate Structures </SectionTitle> <Paragraph position="0"> The basic notions used in Intermediate Structures are RELATION and ARGUMENT. In order to come to adequate meaning representations it has also to be distinguished whether RELATIONs stand for verbs or nominals, therefore the notions VERBSTR and NOMSTR have been introduced in addition. In case of coordinate structures a branching is needed for the ARGUMENTs. It is provided by COORD. Information not needed to treat the Kamp fragment is left out here to simplify the presentation.</Paragraph> <Paragraph position="1"> 3.1.1 Relation nodes and Argument nodes Nodes of type Relation contain the relation name and pointers to first and last ARGUMENT.</Paragraph> <Paragraph position="2"> Nodes of type Argument contain the following information: type, standard role name, pointers to the node representing the contents of the argument, and to the previous and next ARGUMENTs.</Paragraph> <Paragraph position="3"> Verb nodes consist of a VERBSTR with a pointer to a RELATION. That is verb nodes are Relation nodes where the relation corresponds to a verb.</Paragraph> <Paragraph position="4"> Verb nodes (VERBSTR) contain a pointer to the RELATION represented by the verb* They can be ARGUMENTs, e.g., when they represent a relative clause (which modifies a noun, i.e. is attached to a RELATION in a nominal node).</Paragraph> <Paragraph position="5"> Nominal nodes are Argument nodes where the ARGUMENT contains a nominal element, i.e. a noun, an adjective, or a noun phrase. They contain the following information in NOMSTR: type on noun, a pointer to contents of NOMSTR, congruence information (number and gender), quantifier, a pointer to referent of demonstrative or relative pronoun.</Paragraph> <Paragraph position="6"> 1. An Intermediate Structure representing a sen- null tence is called a sentential Intermediate Struct,~re (SIS).</Paragraph> <Paragraph position="7"> Any well-formed Intermediate Structure representing a sentence has a verb node as its root. 2. An Intermediate Structure with an Argument node as root is called an Argument Intermediate Structure (AIS).</Paragraph> <Paragraph position="8"> An Intermediate Structure representing a nominal is an AIS.</Paragraph> <Paragraph position="9"> 3. If s is a SIS and a is an AIS, then s' is a well-formed SIS, if s' is constructed from s and a by attaching a as last element to the list of ARGUMENTs of the RELATION in the root of s and defining the role name of the ARGUMENT forming the root of a. 4. If n and m are AIS, then n' is a well-formed AIS, if the root node of n contains a RELATION and m is attached to its list of ARGUMENTs and a role name is defined for the ARGUMENT forming the root of m. 5. If s is a SIS and a is an Argument node, then a' is an AIS, if s is attached to a and the argument type is set to VERBSTR.</Paragraph> <Paragraph position="10"> 6. If a and b are AIS and e is an Argument node of type COORD, then c' is an AIS if the contents of a is attached as left part of COORD, the contents of b is attached as right part of COORD, and the conjunction operator is defined.</Paragraph> </Section> <Section position="2" start_page="399" end_page="399" type="sub_section"> <SectionTitle> 3.2 The construction of Intermediate Structures </SectionTitle> <Paragraph position="0"> from parse trees To cover the Ramp fragment the following interpretation routines are needed: PRNAME and NOMEN which map strings of characters to elements of AIS; NPDEF, NPINDEF and blPQUAN which map pairs consisting of strings of characters and elements of AIS to elements of AIS; VERB which maps strings of characters to elements of SIS ; NOM and ACC which operate according to Intermediate Structure formation rule 3; RELCL which applies Intermediate Structure formation rule 5 and then 4; COND which combines a pair of elements of SIS by applying Intermediate Structure formation rule 5 and then rule 3; STMT which maps elements of SIS to DRSs. These routines are applied as indicated in the parse tree and give the desired Intermediate Structure as a result.</Paragraph> </Section> </Section> class="xml-element"></Paper>