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Feature-State pairs

Aspects generally correspond to categories used as adjectives or adjectival expressions. In GALEN, most properties which can describe phenomena are found beneath Feature (e.g. Temperature), and the corresponding values beneath State (e.g. Hot / Cold). However, many single Features can take several values. An example would be the body temperature of a patient, which could be raised, increasing, lower than the last reading and higher than expected (for the condition). The GALEN model must allow a Feature to take only one value from a mutually exclusive set of States (e.g. rising, constant, falling) but simultaneously to take multiple States from any number of such sets (e.g. rising as well as low). The schema for Aspects, therefore is:


for example (in GRAIL notation):

Patient which
  hasTemperatureFeature (Temperature which <
    hasAbsoluteState raised
    hasTrendInState decreasing
    hasQuantity (Quantity which <
      hasMagnitude 39.8
      hasUnits degreesCentigrade

However, it should not be possible to simultaneously link to (Temperature - high) and (Temperature - low). To prevent linking to more than one kind of a single Feature, all attributes linking to a Feature-State pair - such as hasTemperatureFeature above - have single-valued cardinality. However, the cardinality of GRAIL attributes is constant, being determined at the point of their initial declaration. To allow linking to more than one different Feature-State pair (e.g to Shape as well as Temperature), a dedicated, single-valued linking attribute must exist for every Feature: Frequency may only link via hasFrequencyFeature, Shape via hasShapeFeature and so on.

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