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 (specifiers, complements and adjuncts may occur at the left or at the right side), but not the role of constituents (specifier, adjunct, complement, head).

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.