#16 Add rule for lists of objects and number restrictions
The combination of a number restriction with a
list of rabbit objects results in unintuitive OWL. In the sample sentence
'Every Field is adjacent to exactly 2 Buildings and Fences', the valid
translation is that Field is a subclass of things which :
('is adjacent to' exactly 2 Building) or ('is adjacent to' some Fence)
according to the specs. However, other possible interpretations are:
'is adjacent to' exactly 2 Building or 'is adjacent to' exactly 2 Fence
or even:
'is adjacent to' exactly 2 (Building or Fence)
The problem of unintuitive OWL translation is even more so when the list
contains a intersection instead of a union. Sentence 'Every Car has exactly
4 Wheels and Passenger Doors' has the intuitive meaning that Car is a
subclass of things which:
('has' exactly 4 Wheels) and ('has' exactly 4 'Passenger Door'), however
the actual translation is:
('has' exactly 4 Wheels) and ('has' some 'Passenger Door')
A good compromise would be to introduce the following rule on how number
restriction can be used in a list of objects.
Rule: for object lists only the following 3 combinations are valid:
a. all objects in the list have their own number restriction
b. only the first object in the list has a number restriction (this is
used for all other objects in the list).
c. none of the objects in the list has a number restriction.
