[Attempto] [CNL] Should I allow for non-monotonic reasoning?

[Adam Wyner]

Hi Norbert,

On 23 May 2015, at 13:35, Norbert E. Fuchs <fuchs at ifi.uzh.ch> wrote:

> Using the power of Prolog I have extended RACE by auxiliary axioms that perform second-order deductions, concretely aggregation. Thus RACE can deduce
> 
>  John is a man. Johnny is a man. ⊢ There are two men.
> 
> Adding a further axiom establishing that, in fact, Johnny is John, RACE fails.
> 
>  John is a man. Johnny is a man. Johnny is John. ⊬ There are two men.
> 
> Thus I have a case of non-monotonic reasoning. (Note that RACE can still deduce that there is one man.)
> 
> My question to the community is "Should RACE allow for non-monotonic reasoning, or does non-monotonicity have consequences that could confuse RACE users in more complex cases?"

I would say that RACE race should allow for non-monotonic reasoning, but I could see that in some cases allowing such inferences might confuse a user.  That is, if a user is *expecting* or *requiring* or *testing a KB for* monotonic reasoning, then having such inferences would be confusing and then be difficult to trace.  On the other hand, where a user really wants non-monotonic reasoning, then having it would be a big strength.  For me and the uses I have for ACE, having non-monotonicity is key.  That said, there are other ways to do this than building it into a RACE reasoner.

On a related note, I thought that your colleague Rolf already had a non-monotonic reasoner with aspects of FOL (I believe the fragment is only with All-Exists), though that is not in the public domain.  I would be very thumbs up to have a non-monotonic FOL reasoner connected to ACE.

Cheers,
Adam

------------------
Dr. Adam Zachary Wyner
Lecturer
Department of Computing Science
University of Aberdeen