Structural Relations (Linguistic Trees)

Linguistics uses trees quite heavily for drawing out phrase structure. Various terms are defined below (in relation to their computing definition):

Tree Terms


A node a dominates another node b if a is above b in the tree, and they're connected (i.e. a is b's ancestor).

Immediate Domination

a immediately dominates b if a is b's parent.

Exhaustive Domination

a exhaustively dominates its constituent; the set of all leaf nodes that it is the ancestor of. i.e. all leaf nodes reachable from it. It exhaustively dominates this set and only this set (not partial sets or this set + other nodes).

The root node exhaustively dominates all leaf nodes.

Constituents Of

If b is dominated by a we say that b is a constituent of a (i.e. a child or grandchild or {great}grandchild of a.

  • Immediate constituents of a are a's children.

Terms in General

A parent node
A child node (immediately dominated by its mother)
A sibling node (if a and b have the same mother they are sisters).


a precedes b if a is on the same level as b and to the left.

  • Sister-precedence is just precedence that only applies if the two nodes are sisters.
  • Immediate-precedence only applies if the two nodes are adjacent


A node a c-commands all its sister nodes and their children.

  • Symmetric c-command is where two nodes c-command each other (i.e. are sisters).
  • A-Symmetric c-command is hence the opposite.

Grammatical Relations

Using the above we can structurally define subjects and objects of a phrase.

The head of a phrase can never be the subject (it's always the phrase), so it'd be [the table] not [table].


The NP/CP child of a TP


One of the NPs from the VP;

  • If the verb phrase is $V_{[NP\text{_}NP]} \text{ or } V_{[NP\text{_}CP]} \text{ or } V_{[NP\text{_}NP\text{ }PP]}$
    • Then the CP or NP is the direct object
  • Else if the verb phrase is $V_{[NP\text{_}NP\text{ {NP/CP}}]}$
    • Then the second NP/CP is the direct object
    • e.g.

* The CP there is the object.

Object of a Preposition

The NP child of a PP

Indirect Object

The first object indicating the goal of a transfer (so the person you're telling or the place you're putting something).

  • If the verb phrase is $V_{[NP\text{_}NP\text{ }PP]}$
    • Then the PP is the indirect object
  • Else if the verb phrase is $V_{[NP\text{_}NP\text{ {NP/CP}}]}$
    • Then the first NP after the _ is the direct object
    • e.g.

* The second NP there is the object.


Obliques are any additional NP/PPs at the end of a phrase (non-essential to the verb phrase).