Phrase Structure Trees

Good tree drawing tool

General Tree Rules

  • Lines don't cross
  • Words at the base of the tree do not have lines down to them
  • Use paraphrases to disambiguate, but not to draw the trees

The Argument for Internal Structure

  1. Word order is important - "the puppy hit the rock" is different to "the rock hit the puppy"
  2. There's no simple rule to change sentences to yes/no questions. Hypothesising about how we eventually get down to "moving the first auxiliary after the subject to the front of the sentence". Hence we get to needing to know about structure (and grouping of phrases).


We represent internal structure as constituents (any unit of internal syntactic structure that functions together as a group).

Constituency Tests

  • Modification ("red" modifies "ball", hence "the red ball" is a unit)
  • Movement (do the words all move together?)
  • Replacement (can we replace a group of words with one - e.g. "the old man" to "john" or "him")
  • Ellipsis (deleting verbs if there's another near identical with it - "Beth said hi but I don't think bob will (say hi)").
  • Stand Alone (can the phrase stand alone in response to a wh- question?)
  • Conjunction (if two XPs can be joined by '&', then they could be the same X - e.g. "John" and "Big Blue" played blue are obviously not both NPs)

Phrase Structure Rules

\begin{align} XP \rightarrow (YP)\text{ X } (ZP+) \end{align}

The phrase consists of an optional other phrase, a head of phrase and any number of optional other phrases

Noun Phrase Rule

\begin{align} \begin {matrix} NP \rightarrow \text{ (D) N'} \\ N' \rightarrow \text{ (AdjP) N' or N' (PP)}\\ N' \rightarrow \text{ N (PP)}\\ \end{matrix} \end{align}

A noun phrase consists of an optional determiner and then any number of adjectival/prepositional phrases, a noun (head), an optional prepositional phrase an optional complementiser phrase.

These are all split up with Noun-Bars.

Adjective/Adverb Phrase Rule

If an XP modifies some head Y, then XP must be Y's sister.

e.g. "very red ball" would be:


Prepositional Phrase Rule

\begin{align} \begin {matrix} PP \rightarrow P' \\ P' \rightarrow \text { (AdvP) P' or P' (PP)}\\ P' \rightarrow \text { P (NP)} \end {matrix} \end{align}

The PP goes to any number of optional Adverb Phrase or Prepositional Phrases, and then a Preposition and an optional NP.

The NP being optional is under debate (is "out" in "I threw the garbage out" a valid preposition?)

Verb Phrase Rules

\begin{align} \text{ Flat: }VP \rightarrow \text{ (AdvP+) V (NP) ({NP/CP}) (AdvP) (PP+) (AdvP+)}\\ \begin {matrix} VP \rightarrow V' \\ V' \rightarrow \text{ (AdvP) V' or V' ({AdvP/PP}) }\\ V' \rightarrow \text{ V (NP)} \end {matrix} \end{align}

VPs consist of an optional adverb phrase and a verb (head) followed by an optional Noun Phrase and any number of optional adverb/prepositional phrases, separated with V-Bar's.

Tense Phrases

\begin{align} TP \rightarrow NP (T) VP \end{align}

Sentences have a subject (NP) and predicate (VP). Neither is optional. There's an optional tense/auxiliary marker in the middle.

Complementiser Phrases

\begin{align} CP \rightarrow (Complementiser) TP \end{align}