X-bar theory

The syntactic framework of the UNLarium derives from the X-bar theory , whose general structure is depicted 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 there can be as many XBs as necessary. Specifiers, complements and adjuncts are optional and are themselves syntactically complex, i.e., they correspond to XPs.

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 = noun (head of a Noun Phrase or NP)
• V = verb (head of a Verbal Phrase or VP)
• J = adjective (head of an Adjective Phrase or JP)
• A = adverb (head of an Adverbial Phrase or AP)
• P = preposition (head of a Prepositional Phrase or PP)
• D = determiner (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)

Phrases

PHRASE	STRUCTURE
	XP
	SPEC	XB
		XB		ADJT
		HEAD	COMP
NP		DP	N	PP	JP, PP