Lexical rules are rules for generating lexical entries from base forms of words (lexemes). Examples are rules for generating the past tense form from the uninflected form of a verb and rules for generating the plural form of a noun from the singular form of a noun. The types of lexical rules are defined in the file "enju/types.lil". Instances of lexical rule types are defined in "enju-devel/invlexrule.lil", "enju-devel/lexrule.lil"and "enju-devel/lexcommon.lil". The lexical rule typse found in "enju/types.lil" and their instances found in "enju-devel/invlexrule.lil", "enju-devel/lexrule.lil" and "enju-devel/lexcommon.lil" are all unique to ENJU.
There are two types of lexical rules in ENJU, one for converting lexemes to lexical entries, the other for converting lexical entries to lexems. This is for convering the weak point of corpus-oriented grammar development by increasing the number of lexical entries. Most lexical entries acquired from corpora are the results of some kind of syntactic transformation. In order to extract grammar rules from a corpus, the first thing we have to do is to apply lexical rules in the reverse direction such that lexemes can be acquired from corpora. Then we apply lexical rules in the normal direction to expand the dictionary. Following this approach, we can acquire more lexemes, which further increase the number of lexical entries that can be acquired.
| enju/types.lil | List up the types of lexical rules. All lexical rules are subtypes of the 'hpsg_lexical_rule' type. |
| enju-devel/invlexrule.lil | The interace to mayz: reduce_lexical_template/5 is found in this file. The predicate is used for acquiring lexemes. |
| enju-devel/lexrule.lil | The interfaces to mayz: expand_lexical_template/5 and expand_lexicon/3 for applying lexical rules in the normal direction for acquiring lexical entries from lexemes. |
| enju-devel/lexcommon.lil | Instances of the interfaces for invlexrule, lexrule are found in this file. To be more precise, you can find the order of rule applications, rewriting rules of predicate argument structures and conditions to be satisfied by various types of lexemes in these files |
| Name | Action | Example |
|---|---|---|
| Lexical Rules for Verbs | ||
| singular3rd_verb_rule | Generating the present tense form of a verb to be used with a 3rd person singular noun from the base form of the same verb | |
| no_singular3rd_verb_rule | Generating the present tense form of a verb to be used with a non-3rd person singular noun from the base form of the same verb | |
| past_verb_rule | Generating the past tense form of a verb | |
| prp_verb_rule | Generating the present participle form of a verb from the base from of the same verb | |
| passive_verb_rule | Generating the past participle (passive form) of a verb from the base form of the same verb. The generated lexical entry would take the by phrase formed by the semantic subject and by as a complement. | John must love Mary. -> Mary must be loved by John. |
| drop_by_rule | Remove the by phrase formed by the semantic subject and by from the subcategorization frame of a passive verb | Mary is loved by John. -> Mary is loved. |
| perfect_verb_rule | Generating the past participle (present progressive form) of a verb from the base form of the same verb. | |
| movement_rule | Generating the lexical entry of a transitive verb whose object is moved | I like apples. -> Apples I like. |
| sentence_movement_rule | Generating the lexical entry of a complement-taking verb whose complement is moved. | John said "Hello." -> "Hello" John said. |
| pc_prp_r_sbj_rule | pc_*_rules are lexical rules for handling participle constructions and generating lexical entries used in subordinate clauses. There are eight pc_*_rules, which differ in the following attributes.
|
The weather getting worse, the picnic was cancelled. |
| pc_prp_r_rule | Walking in the park, I run into Hank. | |
| pc_prp_l_sbj_rule | ||
| pc_prp_l_rule | I went through my pocket looking for the key. | |
| pc_passive_r_sbj_rule | ||
| pc_passive_r_rule | Written in plain English, the book is easy to read. | |
| pc_passive_l_sbj_rule | ||
| pc_passive_l_rule | ||
| prp_r_adjunct_rule | Generating a present participle that premodifies a noun phrase. The modified noun phrase becomes the semantic subject of the present participle. | A man runs. -> a running man |
| prp_l_adjunct_rule | Generating a present participle that postmodifies a noun phrase.The modified noun phrase becomes the semantic subject of the present participle. | A man runs in the park. -> a man running in the park |
| passive_l_adjunct_rule | Generating a past participle that postmodifies a noun phrase.The modified noun phrase becomes the semantic object of the past participle. | He broke the window. -> the window broken by him |
| passive_r_adjunct_rule | Generating a past participle that premodifies a noun phrase.The modified noun phrase becomes the semantic object of the past participle. | He broke the window. -> the broken window |
| imperative_rule | Generating the imperative form of a verb. | |
| yn_question_rule | Generating the auxiliary verbs used in yes-no questions. | I can swim. -> Can you swim? |
| gerund_rule | Generating gerunds. | |
| dative_shift_rule(*) | the dative-marked argument of a verb is shifted. | He gave her the book. -> He gave the book to her. |
| inversion_rule | (sentence_movement がかかった状態などから)Inverting the position of a verb and its argument. | "Hello", John said. -> "Hello", said John. |
| insertion_l_rule | Inserting a complement-taking verb and its subject between the fragments of the complement. The complement of the left is the head. | He said, "The president resigned because of the problem". -> "The president resigned" he said, "because of the problem." |
| insertion_r_rule | Inserting a complement-taking verb and its subject between the fragments of the complement. The complement of the right is the head. | He said "The president resigned". -> "The president" he said, "resigned." |
| subject_extraction_rule | Generating the lexical entry of an embedded verb whose subject is questioned. | I think John loves Mary. -> Who do you think loves Mary? |
| extraposition_sbj_rule | Generating the lexical entry of a verb that allows extraposition of the subject. | That dogs bark annoys people. -> It annoys people that dogs bark. |
| extraposition_obj_rule | Generating the lexical entry of a verb that allows extraposition of the object. | I believe the problem to be obvious. -> I believe it to be obvious that the problem is not easy. |
| Lexical Ruels for Dealing with Nouns | ||
| plural_noun_rule | Generating the plural form of a noun from its singular form. | |
| noun_adjective_rule | Generating the modifying noun of a noun-noun compound. | automobile factory |
| Lexical rules for handling prespositions | ||
| content_extraction_rule | Generating the lexical entry of a preposition whose objectis moved. | I stayed at the hotel. -> which hotel did you stay at? |
| Lexical rules for handling adverbs and adjectives | ||
| comparative_rule | Generating lexical entries of comparatives. | |
| superative_rule | Generating lexical entries of superlatives. | |
Lexical rules can be applied to all words. rules marked by (*) are special rules that can only be applied to some verbs considered to be appropriate in the training corpus.