[zozbot234]

> Commonsense reasoning involves a lot of "Alice thinks that Jane thinks that..." and "A was true until 12:30 this afternoon, now A is false".

These are both examples of modalities. From a formal point of view, description logics are special cases of multi-modal logics. The semantics of these can in turn be understood as computationally well-behaved restrictions of FOL, where the logical quantifiers are understood to range over so-called "possible worlds".

[j-pb]

The issue with the DL approach to FOL fragments is that the operator-subset approach is too coarse grained. We need something more finegrained that allowes for syntactic and semantic constraints over the specific interpretations and theories. An example of such an approach is stratified negation in datalog. DL would simply ban negation or recursion, but limiting the syntax of datalog programs allows for correct semantics while still allowing solutions for many interesting problems.

One of our running gags is: "Snomed might not be able to give you a diagnosis on why you are sick, or provide you with a treatment plan, but thanks to the power and efficiency of description logics it can tell you that you leg bone is connected to your hip bone and that both are bones 80 billion times per second."

[PaulHoule]

It is fun with snomed to track a blood vessel in the periphery all the way to the heart and back.