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Senses, synsets and ontology mapping in WordNet

From: John McCrae <jmccrae@cit-ec.uni-bielefeld.de>
Date: Tue, 16 Apr 2013 10:58:19 +0200
Message-ID: <CAC5njqpsHXQC52qrtWqxkSkXMVYDL1T=osp-D6W+GwHdBsLurw@mail.gmail.com>
To: Philipp Cimiano <cimiano@cit-ec.uni-bielefeld.de>
Cc: public-ontolex <public-ontolex@w3.org>
Firstly, I think an important point here is that WordNet does in fact have
senses as a concept distinct from Synsets and Words. These senses have
their own identifiers and are used for stand-off annotation in WordNet


It seems clear that this index scheme should be preserved as well as, in
the sense that there should be a named resource (URI) for each sense index
(bar the obvious technical limitation that we can't use % in URIs like in
the original schema).

Therefore the chain in the model should be at least

<cat:v> -> <cat%2:29:0::> -> <VerbSynset76400>
Entry -> Sense -> Synset

How we then go to the ontology is an open question

We could then add a further (4th) link onto an ontology, or link from the
same sense as a second reference.

The issue really seems to resolve around how close the concept of a synset
or SKOS concept hierarchy corresponds to that of an ontology. In my opinion
I would argue that the distinction is really in *precision not level*. By
which I mean at the semiotic level that is they both represent the *
reference* in the sense of the abstract concept of "cat" in the same way
that both "cat", "felis catus", "Katze", "gato" and "猫" can refer to the
same set of entities in the world. The key difference is that the synset
hierarchy does not constitute a logic program like an ontology does, in the
sense that the hypernym relations are not transitive and key distinctions
between classes, individuals and qualities are not made.

This understanding would lead me to conclude that the modelling of both the
synset and ontology hierarchy at the same "level" (i.e., both as reference
of the sense) with a different "model" (SKOS vs. OWL) is most appropriate.


On Tue, Apr 16, 2013 at 10:24 AM, Philipp Cimiano <
cimiano@cit-ec.uni-bielefeld.de> wrote:

>  Armando, all,
>  re point 3: about whether to use our three-entity path for modelling
> WordNet
> Concerning the path word - sense - concept (to simplify things a lot).
> Sense represents the meaning of "word" when understood as referring to
> concept "concept".
> Technically, we agreed that sense represents a reification of the pair of
> word/concept and thus allows to attach
> information that relates to the pair rather than to the word or the
> concept.
> Now turning to the modelling of WordNet:
> I agree that in some sense the three-entity path seems an overkill for
> modelling WordNet. But I think that our goal should be to design a model to
> works for all cases and not tune the model to the particular case of
> WordNet. So I would prefer to use the same modelling (i.e. the three-entity
> path) across all specific resources.
> Assuming that WordNet contains a conceptualization, each synset indeed
> represents a skos:Concept (a unit of thought) and in that sense it seems
> reasonable to see a Synset as a reference.
> WordNet provides a definition (gloss) for each synset, which has an
> extension in terms of senses that constitute this synset.
> WordNet does not define in more detail the meaning of a particular
> word/sense that belongs to a synset, but it could in principle.
> So just because WordNet does not distinguish in more detail the specific
> meaning of words when referring to the concept represented by the synset
> our model should not be limited in this sense I think.
> Further, using the "sense" object will allow us to order the senses in
> terms of frequency of usage for each word. Note that this order is exactly
> one of these attributes that neither applies to the word nor to the synset,
> but to the pair of word and synset and would be most naturally attached to
> our sense object.
> Finally, concerning your specific example, it could be modelled as follows:
> <cat:v>
>                a lemon:LexicalEntry
>                lemon:sense <cat::2:29:0::>, <cat::2:35:0::> , <cat_new>
> <cat::2:29:0::>
>                a lemon:LexicalSense ;
>                lemon:reference <VerbSynset76400> .
> <cat_new>
>                a lemon:LexicalSense;
>                lemon:reference myont:vomit .
> So in some sense, both myont:vomit (btw. why "vomit"? ;-)) and <VerbSynset76400>
> have the same status in the lexicon as a concept (skos:Concept) that can be
> the reference for a word. I do not see any problem with that. Of course,
> this does not say anything about the further status or relation between
> these two concepts.
> Enough for now on this point I think.
> Does this all make sense?
> Philipp.
> Am 15.04.13 19:41, schrieb Armando Stellato:
>  Hi all,****
> First of all, thanks John for providing the example: through concrete
> examples it is easier to discuss!****
> ** **
> A few comments (the same “disclaimer” from Elena holds for me: hope I
> didn’t miss anything from other discussions, and in case, sorry in advance).
> ****
> ** **
> 1)      First of all (sorry a bit out of topic), I would ask for a
> clarification, so that I can apply the policy to my examples too: I see the
> “lemon:” prefix being used in many examples, and Lemon is an outcome of
> Monnet project. Is it also the definitive name (or a temporary name) we are
> giving to the model we are developing in this community group? I’ve been
> using “ontolex:” as a fictitious prefix in my examples, and just got
> “lemon” was being used by some of you, because those of you working on
> Monnet have started right from examples they already built in the original
> lemon. Sorry for asking what seems to be trivial, but I never got any
> definitive statement on this, so, better to realign late than never :-D
> Btw, what is written at the last row of: http://www.lemon-model.net/ seems
> to confirm my hypothesis.
> ****
> ok..back to the original topic. Consider that a few of these observations
> can actually be solved by completing the example, and do not necessarily
> clash with it (or, at least, do not clash with what has been already
> written, while I don’t know of what was thought for the rest).****
> ** **
> 2)      With respect to Wordnet (which has explicitly ordered senses per
> word, where I think this order originates – at least for some of the words
> – from frequencies in SemCor) the sense ordering is lost: the synsets are
> bound to the words by means of the sole listing of values, which in plain
> RDF is unordered.****
> ** **
> 3)      This is the most important observation: the use of lemon:sense .
> Together with lemon:reference, lemon:sense should realize the bridge from
> lexical entries to conceptual entities (of the domain ontology). Should we
> use it reach the conceptual entities (e.g. synsets) of the lexical resource
> AS WELL?. In terms of black-box compatibility, as we are modelling even
> conceptual info of lexical resources (e.g.  synsets in wordnet) through
> some RDF language (e.g. SKOS), the thing is legal (the rdfs:range of
> lemon:sense, providing it is wide enough, is respected), still I’m not sure
> we want that. Shortly, I’m not sure if we want to apply exactly the same
> 3-entities approach we are using for the lexicon-ontology model, to
> modelling solely a lexical resource.
> Let’s make an example. We have myont: which is a domain ontology (where we
> have the entry myont:vomit) we are enriching with lexical content, possibly
> from wordnet. Then we have the necessity of representing a direct linking
> between some lexical entries (which may happen to be in wordnet or not) and
> the domain entities of myont.
> We would have thus this example, which I derived from both the WordNet
> example, and the generic OntoLex example for enriching an ontology with
> lexical content:
> <cat:v>
>                a lemon:LexicalEntry
>                lemon:sense <cat::2:29:0::>, <cat::2:35:0::> ;
> <cat::2:29:0::>
>                a lemon:LexicalSense ;
>                lemon:reference <VerbSynset76400> .
>                lemon:reference myont:vomit .
>                                ****
> Note that I’ve cut from the original example, the triples which are
> non-useful to the discussion.****
> Actually, in writing this revised example, I’m not even sure if the two
> lemon:references should be put under the same sense umbrella, or I should
> have used two different senses. This is mainly because I’m not sure about
> the concept of “sense” here and what it represents. I see potential for
> confusion even by looking at the Elena/John emails, as she rightly asks
> about the use of skos:definition instead of lemon:definition. While I’m not
> addressing here the use of a property or the other, the answer by John,
> hinting at the fact that there could be two definitions, one for a sense,
> and one for a synset (and consider that there could be a definition for the
> element in the ontology), makes me wonder how many levels we should have!
> Without delving too much in the appropriateness of this indirection for
> what concerns the lexicon-ontology interface, and considering the sole
> context of the representation of Wordnet (thus just the lexicon
> perspective), to me the path from the LexicalEntry to the Synset is too
> long. In wordnet we just say that a word is linked to a synset: period
> (modulo the addition of an ordering). In particular, “sense” is a relation
> which just tells me that synsetX is the i-th sense of word Y (and there’s a
> many-to-many rel between words and synsets).
> …and this brings me back to our first discussions about the choice of the
> term sense, when referring to the path from lexical entries to ontology
> elements and about the nature of “elements-in-the-middle”.
> In my view (to avoid terminological problems, I focus here on the path
> between entities, and do not name the linking properties at all, so pls
> consider all the arrows here have properties behind, in particular
> lemon:sense and lemon:reference), when considering a mapping between a
> lexical resource such as Wordnet, and an ontology, I would have seen such a
> path:
> LexicalEntry --> Synset --> OntologyResource
> where, without using WordNet, the path would have been:
> LexicalEntry --> [] --> OntologyResource
> with [] a blanknode creating this gluing between them.
> The second line is identical to what we have done until now and what has
> been written in the examples in the “Specification of
> Requirements/Lexicon-Ontology-Mapping”. In particular, the blanknode is an
> instance of that element-in-the-middle (see: “Need for an object between
> Lexical Entry and Ontology”) which still has not a name (and maybe it does
> not need to have, see point 4 below). The first line is thus my
> interpretation of how WordNet would have fit into that general template
> (different from John’s example).
> So, my idea would be to not replicate the complex lexicon-ontology linking
> inside WordNet itself, and have instead a direct linking between lexical
> entries and Synsets, and have THEN, outside of WordNet, a further link to
> an ontology element. If you look at the two rows above (and how the WordNet
> case fits the general case), this is pretty elegant, and does not introduce
> a further level of indirection which appears not necessary. Plus, with this
> method, the link from synsets to ontology elements is a necessary step to
> instantiate the path above, while in the other case, you should introduce
> it as an additional (and probably redundant) triple. You can see it in fact
> in the turtle code above, which I modelled following both the general
> example in “Specification of Requirements/Lexicon-Ontology-Mapping” and
> John’s example on WordNet: there, VerbSynset is a separate entity from
> myont:vomit. Actually, in that view, WordNet would become a separate
> “ontology” which could then be mapped to a domain ontology, instead of
> taking all the benefit of being seen as a lexical resource that can be
> used, seamlessly within our model, to enrich a domain ontology.
> ****
> 4)      IMHO, we should coin a specific vocabulary for each element of
> the lexicon model, and then inherit (where appropriate) from SKOS/SKOSXL,
> to distinguish such elements which belong only to a lexical resource from
> those of any generic KOS. In the wiki, John wonders if what I called
> “SemanticIndex” is not a skos:Concept, and I reply: “yes it is, in fact my
> proposal is that our vocabulary for describing lexical resources can
> inherit from the SKOS/SKOS-XL one”. If you look at the example, even John
> did this, as the LexicalForm is nothing different from a skosxl:Label
> (where lemon:writtenRep could be replaced by skosxl:literalForm) though it
> may be worth creating a dedicated class. I would thus suggest:
> LexicalForm rdfs:subClassOf skosxl:Label
> but to use skosxl:literalForm instead of lemon:writtenRep
> maybe, in this specific case, we can even not reinvent a name, and totally
> reuse the skosxl:Label, which after all is not so bad and pretty fitting
> our necessities… (as it is already related to something specifically
> thought for language).
> On the contrary, for LLD, I would necessarily restrict the class
> skos:Concept to the class of elements which we expect to host things like
> the WordNet Synset class. You can see my sample extension-point above in
> the wiki (“Examples of Modelling in RDF (Alternative approach)”), though by
> now mean I suggest <SemanticIndex> (that was a placeholder, taken from a
> previous work), but in any case I think “Sense” is not appropriate
> (lemon:sense well evokes the sense relation, while I don’t like to see a
> class of “Senses”, that is, to me being a sense is more a role in a given
> relationship, than a intrinsic property of an object).
> ****
> a.       While I think that a more-specific-than-skos:Concept class would
> be welcome for Lexical Linked Data (such as WordNet), and thus put in the
> middle of the: LexicalEntry --> ??? --> OntologyResource  template, I’m not
> sure that the lemon:sense (first arrow) should be necessarily restricted to
> it. John’s use of skos:Concept in the middle suggested me that even a
> generic well-lexicalized KOS could be used for providing LexicalEntries and
> Senses to enrich an ontology. However, I’m still thinking about it…
> ****
> 5)      Another thing which comes to my mind, quite out of the WordNet
> example, but not without consequences for it... What should be, in general,
> the expected modelling behaviour when we have two terms which coincide, but
> the syntactic use of which can follow different paths?
> E.g., suppose we have a term with three senses. In the context of these
> senses, with two of them (say 1 and 2), the term has exactly identical
> variations (declensions for nouns pronouns and adjectives and conjugations
> for verbs ), and maybe other information in common (think about
> etymology!), while for the third sense, this may show differences in the
> variations (e.g. a noun would have a different plural form, or a verb has a
> different form in only one tense, when used with that sense). Should we
> model them as 3 different lexical units, or should we agglomerate the two
> identical ones into one LexicalEntry, and link it to senses 1 and 2?
> This seems to be not related to modeling WordNet in the specific, because
> variations, declinations etc.. are out of WordNet. However, this may affect
> a model trying to reuse WordNet enriched with further information… Thus
> it’s important when we consider how a WordNet modelling could be ported
> inside an extended framework with no risk of inconsistency.
> I just thought about a solution for this: if we allow for skosxl:Labels to
> be directly attached to Synsets (or whatever it is the superclass for
> them), and then we state the following rule:
> LexicalEntry -> lemon:canonicalForm -> skosxl:Label
> LexicalEntry -> lemon:sense -> <asynset>
> ------------------------------------
> skosxl:Label -> ???:sense (whatever it is called) -> <asynset>
> this would allow for the complex structure we expect in general, but also
> allow for a more neutral fit of WordNet. In fact, instead of having the
> third triple as inferred, for WordNet we could just explicitly mention the
> third one, and do not put potentially compromising information (which, in
> any case, is out of WordNet, as noted by John in his reply to Elena).
> The “???:sense (whatever it is called)” could even be lemon:sense itself,
> providing that its range is LexicalEntry+skosxl:Label.
> However, I still have to think more about that…****
> ** **
> One more thing, observation in point 2 above made me think once more that
> we should be clearer in our objectives:****
> Fact: since we have to model ontology-lexicon interfaces, and there isn’t
> much out there for representing lexical info (limited to RDF, I mean); we
> have thus to provide a model for the linguistic part, before “attaching” it
> to the ontology part. Now, the objective could be:****
> ** **
> 1)      We want to model lexical knowledge, and we give a model for this.
> WordNet may be (in part) more fine grained than our model…no big trouble,
> WordNet is WordNet, and our model is our model… we’ll be missing those
> details..****
> a.       A slightly different interpretation of the above: we want to
> model lexical knowledge, AND we decide WordNet IS the model (at least for
> the monolingual word-description needs..I leave out FrameNet et similia
> from this context of discussion). No big deal with other alternative
> resources to WordNet..****
> 2)      We want to model existing lexical resources. Thus WordNet, as
> well as other resources (maybe differently organized) are all important***
> *
> ** **
> Obviously, there are endless colours in the middle of the above, as we
> could be in case 1 or 2, and still think WordNet is so important that it
> has to be fully covered (also because, in this way, Princeton could decide
> to natively output each new release of WordNet in RDF too according to our
> model).****
> ** **
> Cheers,****
> ** **
> Armando****
> ** **
> P.S: I’ve brought a couple of small fixes to the page:
> http://www.w3.org/community/ontolex/wiki/Specification_of_Requirements/Lexicon-Ontology-Mapping#Summary_on_Requirements_on_the_Lexicon-Ontology-Mapping_.28Synthesis_by_PC.29 which
> we already discussed 2 or 3 meetings ago.****
> ** **
> ** **
> *From:* johnmccrae@gmail.com [mailto:johnmccrae@gmail.com<johnmccrae@gmail.com>]
> *On Behalf Of *John McCrae
> *Sent:* venerdì 12 aprile 2013 16.10
> *To:* public-ontolex
> *Subject:* WordNet modelling in Lemon and SKOS****
> ** **
> Hi all,****
> ** **
> Here is the proposed modelling of WordNet as lemon and SKOS (using
> skos:Concept for synsets)****
> ** **
> http://www.w3.org/community/ontolex/wiki/Specification_of_Requirements/Linked_Data#Example:_WordNet_as_lemon-SKOS
> ****
> ** **
> Any comments?****
> ** **
> Regards,****
> John****
> --
> Prof. Dr. Philipp Cimiano
> Semantic Computing Group
> Excellence Cluster - Cognitive Interaction Technology (CITEC)
> University of Bielefeld
> Phone: +49 521 106 12249
> Fax: +49 521 106 12412
> Mail: cimiano@cit-ec.uni-bielefeld.de
> Room H-127
> Morgenbreede 39
> 33615 Bielefeld
Received on Tuesday, 16 April 2013 08:59:58 UTC

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