Constituent combinations are licensed by the notion of headedness. The notion of headedness assumes that the head features of a lexical item are structure shared with the maximal projection of that phrase. Thus a Verb-Phrase for example will have access to all information in the path SYNSEM.LOCAL.CAT.HEAD pertaining to the verb that is its head. As we have seen in the previous section, the lexical specification of a lexical item may constrain the lexical item to combine with other signs in other to fully express its meaning in a stand alone utterance. Now, ordering in how such signs are combined is important and this achieved by a constraint on the type phrase that it
mother and the elements on the ARGS list are the daughters. Most phrases are of the type headed-phrase and this constrains the value of the attribute HEAD to be re-entrant with the value of the head daughter as in (102):
(102)
A headed phrase with one daughter is called a unary-phrase and is composed through a unary-rule and a phrase with two daughters is called a binary- phrase and composed by a binary-rule.
A unary-rule constrains a phrase to have its NON-HEAD-DTR to be an empty-list and the head daughter to be the only element on its ARGS list as in (103):
(103) [ ] [ ]
Unary rules are applicable to cases where a phrasal category consists of only one constituent (as in an intransitive Verb Phrase).18 It is an input output mechanism where the input is the daughter constituent and the output the mother constituent.
A binary-rule constrains - when head-initial - the first daughter on the ARGS list to be re-entrant with the value for head-daughter and the value for the second daughter on the list to be re-entrant with that of the non-head-daughter as in (104) below:
18 It is also applicable to lexeme-to-word-rules which I discuss in the next section.
(104) [ ] [ ]
The daughter and mother values are constrained to be INFLECTED+ ensuring that only word class signs can combine to form larger signs.
Binary-phrases may be head-initial or head-final and this is represented in (105) and (106) below:
In my analysis of multi-verb constructions in chapter 7 the schemata I apply to account for combinations of events in series all inherit from binary-phrase.
The five types of phrases above gives rise to the grammar architecture in (107a) below (cf. Hellan 2003):
(107) i.
I explain (107i) from bottom up, the rule types which all inherit from the type headed-phrase. These rules distinguish sub-types of phrases in terms of relations between the values of their valence features and a NON-HEAD-DTRS list.
The head-complement-rule constrains the value of the attribute COMPS in the mother as an empty list. It has a lexical head as head daughter and all complements of that lexical head must be saturated at the phrasal level. Elements on the COMPS list of the verb are sisters to it.
In (107ii), the symbol ⊕ represents sequence union and appends a list to another list.
The head-mod-rule has the modifier as HEAD-DAUGHTER. This element is selected by an attribute MOD a constraint on the head of the modified
NON-HEAD-DAUGHTER as in (107iii) below:
iii.
[ [ ] ]
The head-subj-rule discharges the subject of the phrase and has the following constraint:
The head-complementizer-rule has a HEAD-DTR with value of type complementizer and it is constrained that at least one of the values for COMPS is a sentence with a saturate SUBJ value. The semantics of the phrase is interpreted from the semantics of the non-head-daughter (V-as saturated phrase in (107i)).
v.
For the head-filler-rule the HEAD-DTR value for NON-LOCAL is non-empty and is the NON-HEAD-DTR value. The attribute that constrains this element to occur in a NON-LOCAL position is SLASH. The value of SLASH on the mother phrase is the union of all its SLASH values as in (107 vi).
vi.
A principle the semantic compositional principle that constrains the C-CONT value of a phrase to have a relationship to the CONT values of one of the daughters is called the head-compositional-phrase. The C-CONT value is the semantic contribution of the phrase itself. It may (but not necessary) be identified with the HOOK of one of its daughters and in (107vii) below, it is identified with the HEAD-DTRs HOOK value:
vii. ⎥⎥⎥
This constraint ensures that the semantics of the phrase will be identified with that of its head daughter.
I have discussed the HPSG theoretical frame-work in this main section and shown how it can be adapted to fit with Èdó valence patterns in section 1.4.6.4. The valence declaration I am applying for this dissertation is as specified by (Hellan 2003). This declaration enables a consistent and uniform account for local and non-local
realization of arguments and their selection for tone and tense features explained in terms of saturation or non-saturation of the VAL values, and the type qval enables me to keep track of arguments through the grammatical function list that remains constant irrespective of the saturation or non saturation of a predicate’s argument on the VAL list. I now discuss the type tam in Èdó in Chapter 2.