X-bar theory

Syntax is the study of the principles and rules for constructing sentences in natural languages.

X-bar theory

The syntactic framework of the UNLarium derives from the X-bar theory , which postulates that all human languages share certain structural similarities, including the same underlying syntactic structure, whose abstract configuration is depicted in the diagram below:

    XP
   / \
spec  XB
     / \
    XB  adjunct
   / \
  X   comp
  |
head

In the above:

• X is the head, the nucleus or the source of the whole syntactic structure, which is actually derived (or projected) out of it.
• comp (i.e., complement) is an internal argument, i.e., a word, phrase or clause which is necessary to the head to complete its meaning (e.g., objects of transitive verbs)
• adjunct is a word, phrase or clause which modifies the head but which is not syntactically required by it (adjuncts are expected to be extranuclear, i.e., removing an adjunct would leave a grammatically well-formed sentence)
• spec (i.e., specifier) is an external argument, i.e., a word, phrase or clause which qualifies (determines) the head
• XB (X-bar) is the general name for any of the intermediate projections derived from X
• XP (X-bar-bar, X-double-bar, X-phrase) is the maximal projection of X.

A key assumption of X-bar theory is that branching is always binary, if it occurs. This means that specifiers, complements and adjuncts are optional and that there can be as many XBs as necessary:

XP | XB | head

XP / \ spec XB | head

XP | XB / \ head comp

XP | XB / \ head adjt

XP / \ spec XB / \ head adjt

XP / \ spec XB / \ XB comp / \ X comp | head

XP / \ spec XB / \ XB adjt / \ XB comp / \ X comp | head

The X-bar theory is claimed to describe a universal principle of natural languages, which is subject to language specific parametrization concerning the order of the constituents (left specification x right specification, left adjunction x right adjunction, left complementation x right complementation), but not the role of constituents (specifier, adjunct, complement, head) or the possible heads.

Heads

In the UNLarium approach to the X-bar theory, the heads, which should replace the letter X, and which define the nature of the phrase, may be occupied by the following categories

• N = nouns and nominals: personal pronouns, demonstrative pronouns, nominalizations, etc (head of a Noun Phrase or NP)
• V = verbs (head of a Verb Phrase or VP)
• J = adjectives (head of an Adjective Phrase or JP)
• A = adverbs (head of an Adverb Phrase or AP)
• P = prepositions (head of a Prepositional Phrase or PP)
• D = determiners: articles, demonstrative determiners, possessive determiners, quantifiers (head of a Determiner Phrase or DP)
• I = auxiliary verbs (head of an Inflectional Phrase or IP)
• C = conjunction (head of a Complementizer Phrase or CP)

Specifiers

Specifiers are used to narrow the meaning intended by the head:

• articles: the (book), a (book), etc.
• possessive determiners: my (book), your (book), etc.
• demonstrative determiners: this (book), that (book), etc.
• quantifiers: no (answer), every (hour), etc.
• intensifiers (emphasizers, amplifiers, downtoners): very (expensive), quite (well), nearly (under), kind of (like), etc.
• frequency adverbs: always (go), never (go), usually (go), etc.
• negative adverbs: not (go)

Complements

Complements are used to complete the meaning intended by the head:

• direct objects: (do) something, (give) something
• indirect objects: (laugh at) something, (give to) someone
• complement of deverbals (i.e., nouns deriving from verbs): (construction of) the city, (arrival of) Peter
• complement of adjectives: (loyal) to the queen, (interested) in Chemistry
• complement of adverbs: (contrarily) to popular belief, (independently) from her
• complement of prepositions: (under) the table, (after) today
• complement of conjunctions: (and) Peter, (I don't know if) he'll come

Adjuncts

Adjuncts are used to modify the meaning intended by the head:

• adjectives: beautiful (table)
• manner adverbs: speak (slowly)
• prepositional phrases: (table) of wood

etc.