Validation of Feature Structures

• Constraints can be applied at three levels

  • in the XML schema (e.g. empty <f> is not allowed)
  • by supplying additional rules in an established XML constraint language (e.g. Schematron)
  • by defining a complete FSD or equivalent

• Or, a given set of <fs> could be “de-abstracted” to form a structure for which a specific schema could be written

• Essential to support “typing” and “sub-typing” of feature structures