1. Syntax
Lecture 1:
X-bar Theory

2. 2 Basic rules
X2  Y2 X1
X1  X0 Y2

3. 2 Basic rules
X2  Y2 X1
X1  X0 Y2

4. 2 Basic rules
X2  Y2 X1
X1  X0 Y2

5. The Meaning of X and Y X and Y are category variables
They stand for any category: N, V, A, P, etc.
The rules are therefore very general:
They govern phrases of any category

6. The difference between X and Y
In the rules, X appears on both sides of the arrow:
Whatever category X stands for on one side, it will stand for the same category on the other
This means that a phrase of category X will always contain a constituent (ultimately a word) of category X
This word is called the head of the phrase
The Y is a non-head constituent
It can be of any category, but it doesn’t have to be the same as X

7. The difference between X and Y
Head

8. An Important Consequence
All phrases have heads
There is only one place a head can go
In the head position
So:-
For every phrase there is a head and for every head there is a phrase

9. What are the numbers all about?
The head (X0) is at the bottom of the tree
X0 is a word
X2 is at the top
So X2 = XP
X1 is smaller than a phrase, but bigger than a word
The numbers just mark the level:
Word (0) – intermediate (1) – phrase (2)
Every phrase has these three levels

10. How come there is not just one phrase?
Words which head phrases have different properties – they have different categories for one thing.
If a noun heads a phrase, it will be a noun phrase
If a verb heads a phrase, it will be a verb phrase
Etc.

11. How come there is not just one phrase?

12. How come there is not just one phrase?

13. How come there is not just one phrase?

14. How come there is not just one phrase?

15. Projection
We say that the properties of the phrase are projected from the lexical head
Each level is therefore called a projection level
X0 is the zero level projection
X1 is the intermediate projection
X2 is the maximal projection

16. The Complement Position
X1  X0 Y2
This rule introduces the head AND a phrase which follows it
This phrase is called the complement
Heads and complements have a very special relationship
The head determines what the complement will be by placing restrictions on it
If the head does not take a complement, the position does not appear

17. The Complement Position
Head selects a complement
Head does not select a complement

18. The Complement Position

19. The Specifier Position
X2  Y2 X1
This rule introduces the intermediate projection AND a phrase that precedes it
This phrase is called the Specifier
The appearance of the specifier is not determined by the head, but specifiers are not always present

20. The Specifier Position
Phrase with a specifier
Phrase without a specifier

21. The Specifier Position

22. Four possible structures

23. A simple demonstration

24. A simple demonstration

25. A simple demonstration

26. A simple demonstration
NP analysis
DP analysis

27. A simple demonstration
Which of these structures is correct?
This has been a much debated question since the 1980s
We will return to this issue in another lecture

28. Notational Variants
There have been other ways used to represent these ideas:
The bar notation:
X0 = X
X1 = X (pronounced ‘X-bar’)
X2 = X (pronounced ‘X-double bar’)
The prime notation: X X’
X’’

29. X-bar theory
Because the bar notation was the first one to be used (Chomsky 1970), the general theory of phrase structure is known as ‘X-bar Theory’
Because the prime notation is easiest to type, it is the most common one used
All three notations express exactly the same concepts

30. Summary Head Complement Specifier obligatory word in every phrase
determines the category of the phrase
selects for complements
Complement
optional phrase following the head (as determined by the head)
restricted by the head
sister to the head
Specifier
optional phrase preceding the head
sister to the intermediate projection (X’)