Review of Direct Semantics (ACTION 314)

Hi!

This is my review of the Direct Semantics. This document has already been in a good shape months ago, when I first reviewed it, and so it is now. I have only found smaller things, none of them critical.

Note: I did not check against Thomas' review that arrived a bit earlier, so there may be overlap.

* General: The definitions in the document, in particular those in §2.5, are of the form "A if B". While this is a typical convention under mathematicians, our documents are targeted to a broader audience. In order to avoid confusion, I suggest to always say "if and only if" (or "iff", and say once that this means "if and only if").

* Abstract: Suggestion: Consider not talking about inference problems in the abstract, but rather move that sentence into the Introduction. It is a pretty technical topic, and I think the abstract should only give a concise and clear hint about the /basic/ purpose of the document.

* §1, 1st par: There is a reference to the Document Overview. I think this is redundant, since the Abstract already mentions it (in the part common to all documents).

* §1, 2nd par: "Since OWL 2 is an extension of OWL DL, ..." Didn't we want to turn away from this statement?

* §1, 3rd par: "The semantics is defined for an OWL 2 axioms and ontologies, [...]". Something is grammatically wrong with this sentence.

* §1, 4th par: "OWL 2 allows for annotations of ontologies, [...], and other annotations." The last part of the sentence sounds confusing (to me). I guess you mean "annotations of annotations". If yes, then why not simply say so?

* §2.1, before the list concerning datatype maps: The sentence ends with "with the following components.", i.e. with a ".". In other places, e.g. the following list for "vocabularies", there is a ":" instead. Consider being coherent.

* §2.1, list of items (and other places): I always wondered why the pairs, such as "< F v >" and "< LV DT >" do not contain a comma, while other pairs later in the document do have a comma? Consider being coherent.

* §2.1, datatype maps, last item: I find the name "facet value" somewhat confusing, since (a) it is actually a set and (b) I rather would expect the "v" in a pair "< F v >" to be called the "facet value". I wonder if there is a better name for this, but have to admit that I do not really have an alternative. If this is going to change, than other documents might need to be changed, either.

* §2.1, vocabularies, 3rd item: Typo: "owl:bttomDataProperty" (missing "o").

* §2.1, vocabularies, 4th item: Are you sure that V_I contains anonymous individuals, which are existential variables?

* §2.2.2: "An n-ary data range DR is interpreted as an n-ary relation (DR)^DT over Δ_D." Please be more explicit what this means, just as you are more explicit earlier in this paragraph on what "unary relation over DELTA_D" means, namely "(DT)^DT subset DELTA_D". You probably mean "(DR)^DT subset (DELTA_D)^n"?

* §2.5, "decidability": "Each class expression of type [...] can contain only object property expressions that are simple [...]". I wonder why there is such a detailed statement here, and why there isn't just a simple pointer to the Structural Spec? Isn't this duplication of information?

* §3: I'm unclear whether this section is intended to be normative or not? I would rather say that it is informative.

* References: The [OWL 2 Profiles] reference doesn't terminate with a ".".

Cheers,
Michael

--
Dipl.-Inform. Michael Schneider
Research Scientist, Dept. Information Process Engineering (IPE)
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Email: michael.schneider@fzi.de
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