Matthew,
Yes, examining the logical consequences of an ontology is a method of
evaluating accuracy_F. However, the fact that one way to measure accuracy_F
involves logical consequences of an ontology does not mean that the definition
of accuracy_F needs to involve logical consequences of the ontology. After all,
one way to measure the speed of a moving object is using the doppler effect;
but the definition of speed does not mention the doppler effect.
Best
Fabian (01)
On Jan 25, 2013, at 3:53 AM, Matthew West wrote: (02)
> Dear Fabian,
> Yes, but how do we know all the axioms are true? One check you can make is
> that there are no unintended consequences in the inferences.
> Regards
> Matthew
> On Jan 23, 2013 8:08 PM, "Fabian Neuhaus" <fneuhaus@xxxxxxxx> wrote:
>
>>
>>
>>
>> On 28 Dec 2012, at 17:50, Fabian Neuhaus wrote:
>>
>> Second, I don't see the need to explicitly talk about all inferences from
>> the axioms as long as we are concerned with ontology languages that are
>> based on truth-preserving deductive inference systems like Common Logic
> or
>> OWL. If all the axioms in X are true it follows that all inferences from
>> the axioms in X are true.
>>
>>
>>
>> The statement as given is theoretically true but seriously misleading in
>> practice. Belief in it has led to serious harm - e.g. potentially
>> life-threatening errors in medical ontologies. If human beings could
>> recognise all the inferences that follow from a set of axioms, we wouldn't
>> need reasoners. Axioms can be superficially plausible but have unexpected
>> consequences, especially when combined with other superficially plausible
>> axioms. Subtle errors in axioms that are difficult to spot can have
>> disproportionate effects.
>>
>>
>>
>> We can only know that a set of axioms is accurate by examining the
>> inferences that follow from them to see if any are false. (Of course we
>> can't examine all inferences except in trivial cases, but systematic
>> searches for unanticipated inferences is central to the QA of any ontology
>> in which inference plays a significant role.)
>>
>> I have watched top logicians spend hours trying to understand the
>> reasoning that led to an obviously false inference from what seemed an
>> obviously correct set of axioms, even with the help of automatic theorem
>> provers, justification finders, etc.
>>
>> Add to this the difficulties of axioms derived from work by domain
>> experts, no matter how clever the tools, and there is more than ample
>> opportunity for incorrect inferences from apparently correct axioms.
>>
>
>
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