IPOX constraint-based grammars define:
- categories and features
- initial category
- phrase structure rules
Below, some examples are given of each rule type. The examples serve only as an illustration, they are not intended as an analysis of a particular language.
Categories and features
Word => edge.
Foot => edge.
Syl => edge, stress.
vow => stress, voc.
edge => ini, fin.
voc => grv, rnd, height.
Note: only the complex feature structures edge and voc need a separate definition.
FRONT := [voc:[-grv, -rnd]].
SPREAD := [voc:[+grv, -rnd]].
ROUND := [voc:[+grv, +rnd]].
HIGH := [voc:[height=close]].
MID := [voc:[height=mid]].
LOW := [voc:[height=open]].
Note: macro's such as these can be used to make a grammar more readable, easier to modify, as well as to express the fact that there are no front, rounded vowels.
Templates are general descriptions of different kinds of constituents:
- branching constituents
- non-branching constituents
- terminal or empty constituents
- constituents with a weak-strong pattern
- constituents with a strong-weak pattern
Branching or non-branching
[edge:[ini=A, fin=B]] --> [edge:[ini=A, -fin]], [edge:[-ini, fin=B]].
[edge=A] --> [edge=A].
[stress=A] --> [stress=A].
Weak-strong or strong-weak
[stress=A] --> ( / [stress=A]).
[stress=A] --> ([stress=A] \ ).
Note: the feature edge is used to mark the left and right edges of a structure; the feature stress is a head-feature of all categories which define the feature.
Note: the top-level goal for the parser; the feature edge is assigned the interpretation of "edge of a word".
Word --> (Foot / Word).
Word --> Foot.
Foot:[edge:[+fin]] --> ((Syl:[+stress] \ Syl:[-stress]) \ Syl:[-stress]).
Foot --> (Syl:[+stress] \ Syl:[-stress]).
Foot:[edge:[+ini]] --> Syl.
Syl --> (On / Ri).
Notes: in this grammar, the main stress occurs in either the ante-penultimate or the penultimate syllable; a monosyllabic foot is allowed only word-initially.
vow:[FRONT, HIGH] --> "i".
vow:[-stress, SPREAD, MID] --> "@".
Notes: the macro's are expanded during compilation; if all categories between Syl and vow are defined for the feature stress, the templates will assure that schwa can only occur in unstressed syllables.Arthur Dirksen / firstname.lastname@example.org / January 1995