Laurie Bauer - WordPress.com — Get a Free Blog Here

THE LINGUISTICS STUDENT’S HANDBOOK 70
which has more than one branching structure in it. In (4), A dominates D, but
immediately dominates C. Mothers immediately dominate their daughters.
As well as showing dominance relationships, trees like those in (3) and (4) also
(4)
A
B C
indicate linear precedence. In (4), for example, B comes before (to the left of)
D. Although we might be able to envisage a tree in which the branch linking C
to D was lengthened, and B occurred between D and E, it is generally taken
that this would not be a legal tree structure: it would involve crossed branches,
and crossed branches are not permitted.
Although trees show both dominance and precedence relationships, the two
are usually treated together as a single set of relationships. Occasionally, rules
for dominance are distinguished from rules for precedence in an ID/LP
(Immediate Dominance / Linear Precedence) format (Gazdar et al. 1985).
Standard phrase-structure rules (rules of the general form A → b + c) cannot
distinguish between these two aspects of the tree structure, with the result that
it would be impossible to write a standard phrase-structure rule to generate
trees with crossing branches.
Some conventions
D E
Conventionally, syntactic trees are drawn as being binary branching (i.e. no
mother can have more than two daughters) except in instances of coordination.
This is a recent convention, and not necessarily adhered to by all syntacticians.
(For more discussion see section 11.) Binary-branching trees are generally
accepted in morphology, but are not always accepted in phonology, where the
arguments for assigning a binary structure to a sequence of three (or more)
adjacent consonants in a word like sixths may not always be clear. However, even
here, some scholars enforce binary-branching trees, and nearly all scholars
prefer them.
Another convention, again generally accepted in syntax, but not always in
phonology, is sometimes referred to as the Single Mother Convention. The
Single Mother Convention states that every node except the root must have one
and only one mother. This is important for establishing the mathematical
structure of the tree, and seems relatively uncontroversial in syntax and morphology.
In phonology, however, there has been a great deal of discussion of
ambisyllabicity, whereby the medial consonant in a word like silly may be seen
as being simultaneously the coda of the first syllable and the onset of the second
syllable. This accounts for two things: /i/ cannot occur in a stressed syllable in