*Syntactic Theory*

*Syntactic Theory*

# Talking about Trees

Syntactic (and morphological) structure is usually depicted with a tree diagram. Like this one:

Basic structural notions in trees were already explained in the basic module on Syntax. See here!

When talking about trees, the following notions play a role.

- Basic notions:
- node: a
**node**is a position in a tree.

The example tree has twelve nodes. - label: a
**label**is a symbol that is written at the node.

In the example, the labels are either syntactic categories (N, NP, V, Det, VP, S) or words (*Pat*,*likes*,*my*,*cat*). - dominance: A node
*A***dominates**a node*B*if*A*is higher in the diagram than B.

A node*A*dominates a tree*T*if*A*dominates the highest node in*T*. - immediate dominance: a node
*A***immediately dominates**a node*B*if*A*is higher in the tree than*B*and there is exactly one line connecting*A*and*B*(i.e. there is no node*C*such that*A*,*B*, and*C*are distinct nodes and*A*dominates*C*and*C*dominates*B*). - local tree: A
**local tree**is a tree that consists of a node*A*and exactly the nodes that are immediately dominated by the node*A*.

The example tree has eight local trees. These are:S NP VP NP N V Det N / \ | / \ / \ | | | | NP VP, N, V NP, Det N, Pat, likes, my, cat

- node: a
- Tree metaphor:
- root: The highest node in a tree is the
**root**, i.e. the node that dominates all other nodes.

In the example: the root is the node with label S. - leaf: A node at the bottom of the tree is a
**leaf**, i.e. a node that does not dominate any other node.

In the example: the nodes with labels*Pat*,*likes*,*my*and*cat*are the leaves. - branch: A
**branch**of a node*A*is a sub-tree that is connected

In the example, the root node (S) has two branches. The node Det has only one branch.- a binary branching node: A node that has two branches.

In the example: the nodes with labels S and VP are binary branching. Also the rightmost node with label NP is binary branching. - ternary branching node: A node that has three branches.

There is no such node in our example. - non-branching node (= unary branching node): A node that has one branch.

- a binary branching node: A node that has two branches.

- root: The highest node in a tree is the
- Family metaphor:

The following terms relate to local trees such asVP / \ V NP

- mother: A node
*A*is the**mother**of a node*B*if*A*immediately dominates*B*.

In the example, the node with label VP is the mother of the nodes labeled V and NP. - daughter: A node
*A*is a**daughter**of a node*B*if*B*immediately dominates*A*.

The example local tree has two daughters: the nodes with labels V and NP are the daughters of the node with label VP. - sister(s): node
*A*is a**sister**of node*B*if they are leaves in the same local tree.

In the example, the nodes with labels V and NP are sisters.

- mother: A node
- Others:
- yield: The
**yield**of a tree is the series of words that are dominated by the root of the tree in the given order. - precedence: A node
*A***precedes**a node*B*in a tree with root*C*if the yield of the tree dominated by*A*precedes the yield of the tree dominated by*B*in the yield of the tree dominated by*C*.

In the example, the node V precedes the second NP node, because its yield (*likes*) precedes the yield of the NP (*my cat*). However, the V node does not precede the VP node, because the yield of the tree dominated by the V node is part of the yield of the tree dominated by the VP node.

- yield: The

Categories: Glossary