[ontoiop-forum] Call for final comments on DOL, UML

[Till Mossakowski]

Dear Conrad,

many thanks for your comments! Here are my replies:

 > Why not define sets as restricted bags (bags with no duplicates), 
like you did with ordered sets as restricted sequences? Should be at 
least:   (forall (x) (if (form:Set x) (form:Bag x)) plus no-duplicate 
restriction.
Note that I did *not* define ordered sets as restricted sequences. 
Instead, I copied the theory of sequences and modified it. In 
particular, the axiom
// no element can be inserted twice
(forall (x s)
   (if (from:ordered-set-member x s)
       (= (form:ordered-set-insert x s) s)))
cannot be used for sequences.
If wanted, I can try to have a similar sharing of theories between sets 
and bags.

 > Did you intend to support infinite sets? Not that this requires it 
(only allows it), but UnlimitedNatural in UML includes an infinitely 
large value.  See comment about multiplicity in E.4.
No, only finite sets are supported, assuming that system snapshots are 
always finite. Instead of UnlimitedNatural, we could also use natural 
numbers without an infinitely large value. What would be the name of 
such a type?

 > Why not just     (forall (x s)      (form:set-member x 
(form:set-insert x s))) ?
The original axiom is:
(forall (x y s)
   (iff (form:set-member x (form:set-insert y s))
        (or (= x y)
             (form:set-member x s))))
This is much stronger. In particular, from it you can derive 
non-memberships, like (not (form:set-member 2 (form:set.insert 1 
form:empty-set))), provided that 1 is not equal to 2.

 > Not sure I'm reading this correctly, but it seems to say the 
properties involved in a composition association are properties of m, 
whereas they are usually properties of the classes at the ends of the 
association.
We have changed this, see attached corrected PDF.

 > Properties can be composed without being member ends of an 
association.  The UML 2.5 spec describes aggregation in the Property 
subclause (9.5.3), without constraining the properties to be member ends 
of associations.  The phrase quoted here describes a composite property 
with ("grouping its") values.  Feel free to ask Ed and others, this is 
well known to be the interpretation of the spec, and is implemented in 
tools.
We have changed this, see attached corrected PDF.

 > Are the labels n2s, etc, association names?  If so they should be 
capitalized.  If they are property names, they should be closer to one 
of the classes at the end of the line.
Yes, they are association names. We will capitalize them.

 > How are unlimited upper bounds represented?  This could be the 
absence of a bound in DOL, I guess.  In UML, absence of a bound defaults 
to 1, so there's no ambiguity translating to DOL this way.  Where does 
UnlimitedNatural come in?
Yes, unlimited upper bounds are represented by absence of bounds here.

All the best,
Till


Am 15.10.2015 um 21:47 schrieb Bock, Conrad:
> Till, et al,
>
> Here are my comments on the UML appendix.  Let me know if there
> are any questions/comments, can discuss if needed.
>
> Conrad
>
>
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