Constituent (linguistics)
Encyclopedia
In syntactic
analysis, a constituent is a word or a group of words that functions as a single unit within a hierarchical structure. The analysis of constituent structure is associated mainly with phrase structure grammars
, although dependency grammars
also allow sentence structure to be broken down into constituent parts.
Phrase
s (noun phrases, verbal phrases, etc.) are usually constituents of a clause
, but clauses may also be embedded into a bigger structure. For example, in the clause "I didn't hear what you said," the subordinate clause
"what you said" is embedded into the main clause and is syntactically its object; this can be demonstrated by substituting the pronoun
"it" for the subordinate clause "what you said"; the result of this substitution is the clause "I didn't hear it."
(1) a. He is going to attend another language course to improve his English.
(2) a. She bought a pair of gloves with silk embroidery.
(3) a. She bought a pair of gloves with silk embroidery.
(4) a. I don't know the man who is sleeping in the car.
The ungrammaticality of the first changed version and the grammaticality
of the second one demonstrates that the whole sequence, the man who is sleeping in the car, and not just the man is a constituent functioning as a unit.
(5) a. What did you do yesterday? - Worked on my new project.
Linguists do not agree whether passing the stand-alone test is sufficient, though at a minimum they agree that it can help confirm the results of another constituency test.
of the active sentence is changed to the subject
of the corresponding passive sentence:
(6) a. A car driving at breakneck speed nearly hit the little dog.
In case passivization results in a grammatical sentence, the phrases that have been moved can be regarded as constituents.
(7) a. Fred relax at night on his couch.
Since they can be omitted, the prepositional phrases at night and on his couch are constituents.
(8) a. He enjoys writing sentences and reading them.
Based on the fact that enjoys writing sentences and reading them are coordinated using and, one can conclude that they are constituents. The validity of the coordination test is challenged by additional data, however. The sentences (8b) and (8c) suggest that the italicized sequences there should be understood as constituents. Most grammars do not view sequences such as He enjoys in (8c) to the exclusion of the VP writing sentences as a constituent. Thus while the coordination test is widely employed as a diagnostic for constituent structure, it is faced with major difficulties and is therefore perhaps the least reliable of all the tests mentioned.
(9) a. The man was shot.
The ambiguity of this sentence results from two possible arrangements into constituents:
(10) a. They killed [the man] [with a gun].
In (10a) with a gun is an independent constituent with instrumental
meaning , in (10b) it is embedded into the noun phrase the man with a gun modifying the noun man. The autonomy of the unit with a gun in the first interpretation can be tested by the answer fragment test:
(11) How did they kill the man? - With a gun.
However, the same test can be used to prove that the man with a gun in(10b) should be treated as a unit:
(12) Who(m) did they kill? - The man with a gun.
The ability of constituency tests to disambiguate certain sentence in this manner bears witness to their utility. Most of not all syntacticians employ constituency tests in some form or another to arrive at the structures that they assign to sentences.
(=constituency grammar) or a dependency grammar
. Constituency grammars necessarily view each individual word as a constituent, whereas dependency grammars assume that a given individual word is a constituent only if it does not dominate other words. Interestingly, the constituency tests just enumerated support the dependency grammar stance by and large. Consider the example sentence They killed the man with a gun. The individual words killed and with are constituents given a constituency grammar understanding of sentence structure (since every individual word is by definition a constituent in constituency grammars), whereas these two words are not constituents in dependency grammars because they dominate other words. The constituency tests introduced above support the dependency grammar stance in this area:
(13)a. *Killed, they the man with a gun. - Topicalization
(14)a. *With, they killed the man a gun. - Topicalization
The results here are similar for the other tests mentioned above, the one major exception being coordination, which suggests that individual words are in fact constituents, e.g. He beat and killed the man with a gun. Data like (13-14) can influence our understanding of constituent structure. Individual words cannot be blindly accepted as constituents merely because they are words.
Syntax
In linguistics, syntax is the study of the principles and rules for constructing phrases and sentences in natural languages....
analysis, a constituent is a word or a group of words that functions as a single unit within a hierarchical structure. The analysis of constituent structure is associated mainly with phrase structure grammars
Phrase structure grammar
The term phrase structure grammar was originally introduced by Noam Chomsky as the term for grammars as defined by phrase structure rules, i.e. rewrite rules of the type studied previously by Emil Post and Axel Thue...
, although dependency grammars
Dependency grammar
Dependency grammar is a class of modern syntactic theories that are all based on the dependency relation and that can be traced back primarily to the work of Lucien Tesnière. Dependency grammars are distinct from phrase structure grammars , since they lack phrasal nodes. Structure is determined by...
also allow sentence structure to be broken down into constituent parts.
Phrase
Phrase
In everyday speech, a phrase may refer to any group of words. In linguistics, a phrase is a group of words which form a constituent and so function as a single unit in the syntax of a sentence. A phrase is lower on the grammatical hierarchy than a clause....
s (noun phrases, verbal phrases, etc.) are usually constituents of a clause
Clause
In grammar, a clause is the smallest grammatical unit that can express a complete proposition. In some languages it may be a pair or group of words that consists of a subject and a predicate, although in other languages in certain clauses the subject may not appear explicitly as a noun phrase,...
, but clauses may also be embedded into a bigger structure. For example, in the clause "I didn't hear what you said," the subordinate clause
Dependent clause
In linguistics, a dependent clause is a clause that augments an independent clause with additional information, but which cannot stand alone as a sentence. Dependent clauses modify the independent clause of a sentence or serve as a component of it...
"what you said" is embedded into the main clause and is syntactically its object; this can be demonstrated by substituting the pronoun
Pronoun
In linguistics and grammar, a pronoun is a pro-form that substitutes for a noun , such as, in English, the words it and he...
"it" for the subordinate clause "what you said"; the result of this substitution is the clause "I didn't hear it."
Constituency tests
Constituency tests are diagnostics employed to identify the constituent structure of sentences. There are numerous constituency tests applied to English sentences, many of which are listed here: 1. topicalization (=fronting), 2. clefting, 3. pseudoclefting, 4. pro-form substitution, 5. answer fragments, 6. passivization, 7. omission, 8. coordination, etc. These tests are rough-and-ready tools that grammarians employ to reveal clues about syntactic structure. A word of caution is warranted when employing these tests, however, since they often deliver contradictory results. Some syntacticians even arrange the tests on a scale of reliability, with less-reliable tests treated as useful to confirm constituency though not sufficient on their own. Failing to pass a single test does not mean that the unit is not a constituent, and conversely, passing a single test does not mean necessarily that the unit is a constituent. It is best to apply as many tests as possible to a given unit in order to prove or to rule out its status as a constituent.Topicalization (fronting)
Topicalization involves moving the test sequence to the front of the sentence. It is a simple movement operation:(1) a. He is going to attend another language course to improve his English.
- b. To improve his English, he is going to attend another course.
Clefting
Clefting involves placing a sequence of words X within the structure beginning with "It is/was": It was X that...(2) a. She bought a pair of gloves with silk embroidery.
- b. It was a pair of gloves with silk embroidery that she bought.
Pseudoclefting
Pseudoclefting (also preposing) is similar to clefting in that it puts emphasis on a certain phrase in a sentence. It involves inserting a sequence of words before "is/are what" or "is/are who":(3) a. She bought a pair of gloves with silk embroidery.
- b. A pair of gloves with silk embroidery is what she bought.
Pro-form substitution (replacement)
Pro-form substitution, or replacement, involves replacing the test constituent with the appropriate pro-form. Substitution normally involves using definite pro-form like it, he, there, here, etc. in place of a phrase or a clause. If such a change yields a grammatical sentence where the general structure has not been altered, then the test sequence is a constituent:(4) a. I don't know the man who is sleeping in the car.
- b. *I don't know him who is sleeping in the car. (ungrammatical)
- c. I don't know him.
The ungrammaticality of the first changed version and the grammaticality
Grammaticality
In theoretical linguistics, grammaticality is the quality of a linguistic utterance of being grammatically well-formed. An * before a form is a mark that the cited form is ungrammatical....
of the second one demonstrates that the whole sequence, the man who is sleeping in the car, and not just the man is a constituent functioning as a unit.
Answer fragments (question test)
The answer fragments test refers to the ability of a sequence of words to stand alone as a reply to a question. It is often used to test the constituency of a verbal phrase but can also be applied to other phrases:(5) a. What did you do yesterday? - Worked on my new project.
- b. What did you do yesterday? - *Worked on. (unacceptable, so worked on is not a constituent).
Linguists do not agree whether passing the stand-alone test is sufficient, though at a minimum they agree that it can help confirm the results of another constituency test.
Passivization
Passivization involves changing an active sentence to a passive sentence, or vice versa. The objectObject (grammar)
An object in grammar is part of a sentence, and often part of the predicate. It denotes somebody or something involved in the subject's "performance" of the verb. Basically, it is what or whom the verb is acting upon...
of the active sentence is changed to the subject
Subject (grammar)
The subject is one of the two main constituents of a clause, according to a tradition that can be tracked back to Aristotle and that is associated with phrase structure grammars; the other constituent is the predicate. According to another tradition, i.e...
of the corresponding passive sentence:
(6) a. A car driving at breakneck speed nearly hit the little dog.
- b. The little dog was nearly hit by a car driving at breakneck speed.
In case passivization results in a grammatical sentence, the phrases that have been moved can be regarded as constituents.
Omission (deletion)
Omission checks whether a sequence of words can be omitted without influencing the grammaticality of the sentence — in most cases local or temporal adverbials can be safely omitted and thus qualify as constituents.(7) a. Fred relax at night on his couch.
- b. Fred relaxes on his couch.
- c. Fred relaxes at night.
Since they can be omitted, the prepositional phrases at night and on his couch are constituents.
Coordination
The coordination test assumes that only constituents can be coordinated, i.e., joined by means of a coordinator such as "and", e.g.(8) a. He enjoys writing sentences and reading them.
- b. He enjoys writing and she enjoys reading sentences.
- c. He enjoys but she hates writing sentences.
Based on the fact that enjoys writing sentences and reading them are coordinated using and, one can conclude that they are constituents. The validity of the coordination test is challenged by additional data, however. The sentences (8b) and (8c) suggest that the italicized sequences there should be understood as constituents. Most grammars do not view sequences such as He enjoys in (8c) to the exclusion of the VP writing sentences as a constituent. Thus while the coordination test is widely employed as a diagnostic for constituent structure, it is faced with major difficulties and is therefore perhaps the least reliable of all the tests mentioned.
Constituency tests and disambiguation
Syntactic ambiguity characterizes sentences which can be interpreted in different ways depending solely on how one perceives syntactic connections between words and arranges them into phrases. Possible interpretations of the sentence They killed the man with a gun:(9) a. The man was shot.
- b. The man who was killed had a gun with him.
The ambiguity of this sentence results from two possible arrangements into constituents:
(10) a. They killed [the man] [with a gun].
- b. They killed [the man with a gun].
In (10a) with a gun is an independent constituent with instrumental
Instrumental case
The instrumental case is a grammatical case used to indicate that a noun is the instrument or means by or with which the subject achieves or accomplishes an action...
meaning , in (10b) it is embedded into the noun phrase the man with a gun modifying the noun man. The autonomy of the unit with a gun in the first interpretation can be tested by the answer fragment test:
(11) How did they kill the man? - With a gun.
However, the same test can be used to prove that the man with a gun in(10b) should be treated as a unit:
(12) Who(m) did they kill? - The man with a gun.
The ability of constituency tests to disambiguate certain sentence in this manner bears witness to their utility. Most of not all syntacticians employ constituency tests in some form or another to arrive at the structures that they assign to sentences.
Phrase structure vs. dependency structure
The understanding of constituent structure varies greatly depending on whether one adopts a phrase structure grammarPhrase structure grammar
The term phrase structure grammar was originally introduced by Noam Chomsky as the term for grammars as defined by phrase structure rules, i.e. rewrite rules of the type studied previously by Emil Post and Axel Thue...
(=constituency grammar) or a dependency grammar
Dependency grammar
Dependency grammar is a class of modern syntactic theories that are all based on the dependency relation and that can be traced back primarily to the work of Lucien Tesnière. Dependency grammars are distinct from phrase structure grammars , since they lack phrasal nodes. Structure is determined by...
. Constituency grammars necessarily view each individual word as a constituent, whereas dependency grammars assume that a given individual word is a constituent only if it does not dominate other words. Interestingly, the constituency tests just enumerated support the dependency grammar stance by and large. Consider the example sentence They killed the man with a gun. The individual words killed and with are constituents given a constituency grammar understanding of sentence structure (since every individual word is by definition a constituent in constituency grammars), whereas these two words are not constituents in dependency grammars because they dominate other words. The constituency tests introduced above support the dependency grammar stance in this area:
(13)a. *Killed, they the man with a gun. - Topicalization
- b. *It was killed that they the man with a gun. - Clefting
- c. *What they did the man with a gun was killed. - Pseudoclefting
(14)a. *With, they killed the man a gun. - Topicalization
- b. *It was with that they killed the man a gun. - Clefting
- c. *What they did with was killed the man a gun. -Pseudoclefting
The results here are similar for the other tests mentioned above, the one major exception being coordination, which suggests that individual words are in fact constituents, e.g. He beat and killed the man with a gun. Data like (13-14) can influence our understanding of constituent structure. Individual words cannot be blindly accepted as constituents merely because they are words.