- From: Maxime Lefrançois <maxime.lefrancois@emse.fr>
- Date: Mon, 08 May 2017 12:03:17 +0000
- To: Simon.Cox@csiro.au, janowicz@ucsb.edu, rgarcia@fi.upm.es, public-sdw-wg@w3.org, armin.haller@anu.edu.au
- Message-ID: <CALsPASUEnXE-SyehyMN6N5N-yqk88EE=CGvxneP+y4SrmvuZSg@mail.gmail.com>
Hi Simon, all, Let me propose a translation of the ISO 19109 model to RDF: (1) there are Feature-types (classes), and Features of interest (instances of those classes) --> Feature-types are RDFS/OWL Classes, they are sub-classes of sosa:FeatureOfInterest, and their instances are Features of Interest ex1: ex:Room is a RDFS/OWL class that represents a Feature-type, and <roomX> is an instance of that class that represents a Feature (of Interest) ex2: ex:Building is a RDFS/OWL class that represents a Feature-type, and <buildingX> is an instance of that class that represents a Feature (of Interest) (2) there are properties, and these properties may have instances. --> properties are RDFS/OWL Classes, sub-classes of sosa:ObservableProperty (and by transitivity, also of ssn:Property), and their instances are named "property instances". ex: ex:Occupancy is a RDFS/OWL class that represents a Property. <buildingXoccupancy> and <roomXoccupancy> are instances of that class and represent "property instances". Then: (a) a property instance cannot exist in the absence of a feature (of interest) ex1: <buildingXoccupancy> cannot exist in the absence of <buildingX> ex2: <roomXoccupancy> cannot exist in the absence of <roomX> (b) Feature-types (classes) are characterized by a set of properties ex1: ex:Building is characterized by a set of properties, and this set contains property ex:Occupancy ex:Building rdfs:subClassOf [ owl:onProperty ssn:hasProperty ; owl:someValuesFrom ex:Occupancy ] . <buildingX> rdf:type ex:Building ; ssn:hasProperty <buildingXoccupancy> . <buildingXoccupancy> rdf:type ex:Occupancy . (c) But each (well most, anyway) property may relate to more than one feature-type (and implicitly to many more than one individual feature) --> ex:Occupancy can relate to more than ex:Building, it can also relate to ex:Room. ex:Room rdfs:subClassOf [ owl:onProperty ssn:hasProperty ; owl:someValuesFrom ex:Occupancy ] . <roomX> rdf:type ex:Room ; ssn:hasProperty <roomXoccupancy> . <roomXoccupancy> rdf:type ex:Occupancy . To me, everything is fine there: - what is named "xxx-type" is translated in RDFS/OWL as a class - what is named "xxx instance" is translated in RDFS/OWL as an instance ex1: for Feature-type and feature (of interest) - Feature-types are translated in RDFS/OWL as classes - Features (of interest) are translated in RDFS/OWL as instances. ex1: for properties and their instances: - observable (and actuatable) properties are made classes - instances of theses properties are instances. If instead we want to translate ISO 19101 properties into rdf:Properties (or owl:ObjectProperties), then [1] and [2] propose some way to do it, that is totally compatible with the above description. The suggestion would be to translate ISO 19101 properties into both: 1. a sub-class of sosa:ObservableProperty, and 2. a (functional) sub-property of ssn:hasProperty ex:occupancy a owl:ObjectProperty , owl:FunctionalProperty ; rdfs:subPropertyOf ssn:hasProperty ; rdfs:range ex:OccupancyProperty . ex:OccupancyProperty a rdfs:Class ; rdfs:subClassOf sosa:ObservableProperty . ex:Building rdfs:subClassOf [ owl:onProperty ex:occupancy ; owl:someValuesFrom ex:OccupancyProperty ] . ex:Room rdfs:subClassOf [ owl:onProperty ex:occupancy ; owl:someValuesFrom ex:OccupancyProperty ] . <buildingX> rdf:type ex:Building ; ex:occupancy <buildingXoccupancy> . <buildingXoccupancy> rdf:type ex:Occupancy . <roomX> rdf:type ex:Room ; ex:occupancy <roomXoccupancy> . <roomXoccupancy> rdf:type ex:Occupancy . Any comments? Best, Maxime [1] - https://lists.w3.org/Archives/Public/public-sdw-wg/2017Feb/0478.html [2] - https://lists.w3.org/Archives/Public/public-sdw-wg/2017Feb/0515.html Le lun. 8 mai 2017 à 02:49, <Simon.Cox@csiro.au> a écrit : > ISO 19109 model in its revised form says > > (a) A property instance cannot exist in the absence of a feature (of > interest) > > (b) Feature-types (classes) are characterized by a set of properties > > (c) But each (well most, anyway) property may relate to more than one > feature-type (and implicitly to many more than one individual feature) > > This was intended to respect both the ISO 19101 reference model, and the > semantic web toolkit. > > > > When working in the RDFS/OWL world we could just make these observable > (and actuatable) properties RDF properties. i.e. > > > > ssn:Property owl:equivalentProperty rdf:Property . > > > > is OK to me, but because of the way that rdf:Property is built-in to RDF > itself, I’m not sure if the meta-model allows us to go on to say > > > > sosa:ObservableProperty rdfs:subClassOf ssn:Property . > > > > and then > > > > sosa:Observation > > rdfs:subClassOf [ > > rdf:type owl:Restriction ; > > owl:allValuesFrom sosa:ObservableProperty ; > > owl:onProperty sosa:observedProperty ; > > ] . > > > > (or sosa:observedProperty rdfs:range sosa:ObservableProperty . ) > > > > Simon > > > > *From:* Krzysztof Janowicz [mailto:janowicz@ucsb.edu] > *Sent:* Saturday, 6 May, 2017 03:26 > *To:* Maxime Lefrançois <maxime.lefrancois@emse.fr>; Raúl García Castro < > rgarcia@fi.upm.es>; SDW WG Public List <public-sdw-wg@w3.org>; Cox, Simon > (L&W, Clayton) <Simon.Cox@csiro.au>; Armin Haller <armin.haller@anu.edu.au > > > *Subject:* Re: What is a property? > > > > Hi, > > See also Simon's message "In fact in ISO 19109 revision I made sure that > we left the door open for properties to *not* be even tied to just one > feature-type, so that the notion of 'colour' or 'mass' could be denoted > with the same token regardless of which feature-type it is associated with. > i.e. no global domain contraints ..." > > > @Krzysztof, what do you mean by axiomatic perspective ? > > > That from the point of view of the axioms both ways would be acceptable. > > > Are you sure the intended one is really the second example ? Intended by > who ? > > > > > I mean the example where there is one such thing as 'temperature' (which > is an ObservableProperty). Whenever you observe, you may involve different > sensors and carry out your observation on different features. While this > will create a 'new' observation every time, the ObservableProperty will > always stay the same. This is also comparable to the notion of a procedure. > To the very best of my knowledge, this is how all the measurement type code > lists that I am aware of work, e.g., > http://vocab.nerc.ac.uk/collection/A04/current/AverageWindSpeed/. > > Best, > Krzysztof > > On 05/05/2017 09:21 AM, Maxime Lefrançois wrote: > > Hi Krzysztof, Raúl, all, > > > > I will also point to the resources: > > - > https://www.w3.org/2015/spatial/wiki/Link_between_FeatureOfInterest_and_xxxProperty#What_is_an_instances_of_ssn:Property_.3F > > > - https://lists.w3.org/Archives/Public/public-sdw-wg/2017Apr/0336.html > > > @Krzysztof, what do you mean by axiomatic perspective ? Are you sure the > intended one is really the second example ? Intended by who ? > > > > It really looks to me like only (1) conforms to the original SSN spec. > > > > What I love from (1) is that we can indeed, as Krzysztof mentions, express > *both* the Property <OccupancyBuildingX>, and the Property *Type* > ex:Occupancy: > > > > ex:Occupancy rdfs:subClassOf sosa:ObservableProperty. > > <OccupancyBuildingX> a ex:Occupancy ; > ssn:isPropertyOf ns:BuildingX . > > <OccupancyBuildingY> a ex:Occupancy ; > ssn:isPropertyOf ns:BuildingY . > > > > This solution has all the advantages of solutions (1) and (2), while being > perfectly aligned with the original SSN spec, and cover the competency > questions that Raúl and Armin were mentioning. > > > > In addition, Krzysztof brings up one more competency question that (1) > covers, while (2) does not: > > - It is possible to extend SOSA/SSN with some vocabulary to describe for > instance that: "temperature of body1 is less than of body2". With (2), > there is no such concept as "temperature of body 1". > > > > > > So my final suggestion would be to make it clear in the spec and the > examples that we adopt (1). I believe it's little effort to adapt existing > datasets that were using (2) to the (better/original/new) approach (1) > > > > > > Examples will be highly impacted by the final decision to this question, I > will hence delay ACTION-350 until then. > > > > Best, > > Maxime Lefrançois > > > > Le ven. 5 mai 2017 à 17:20, Krzysztof Janowicz <janowicz@ucsb.edu> a > écrit : > > Hi, > > Both uses are okay from an axiomatic perspective, but the indented one > is the second example. It is worth noting that they are not as different > as they may seem because (1) can be made very similar to (2) by adding a > subclassing axiom that states > > Occupancy rdfs:subClassOf ObservableProperty. > > and then change > > ns:OccupancyBuildingX a ssn:Property ; [KJ: should be ObservableProperty] > ... > > to > > ns:OccupancyBuildingX a Occupancy. > > The question is rather how specific we should be to foster > interoperability between different datasets, and, IMHO, we should > clearly state what we mean. There is a 1:2 relation between observable > properties and features (and observations). Science works because no > matter how often we measure the temperature of a body and how many > different sensors and bodies we use, the measured property is of the > same kind, namely temperature. This, for instance, makes sure that we > can state that the temperature of body1 is less than of body2 and so on. > > Best, > Jano > > > On 05/05/2017 07:50 AM, Raúl García Castro wrote: > > Dear all, > > > > Taking a look to a previous thread > > (https://lists.w3.org/Archives/Public/public-sdw-wg/2017Apr/0335.html) > > and to a recent pull request conversation > > (https://github.com/w3c/sdw/pull/792) it seems that there are two > > views on what a property is. > (1) > > Is it something intrinsic to a feature? > > ns:OccupancyBuildingX a ssn:Property ; [KJ: should be > > ObservableProperty] > > ssn:isPropertyOf ns:BuildingX . > > ns:OccupancyBuildingY a ssn:Property ; [KJ: should be > > ObservableProperty] > > ssn:isPropertyOf ns:BuildingY . > > (2) > > Or is it something independent of a concrete feature? > > ns:Occupancy a ssn:Property ; [KJ: should be ObservableProperty] > > ssn:isPropertyOf ns:BuildingX . > > ssn:isPropertyOf ns:BuildingY . > > > > For those familiar with QUDT, is a Property related to a qudt:Quantity > > (first option above) or to a qudt:QuantityKind (second option)? > > > > Note that both options are supported by current definitions and usage > > information, so we need to define clearly what we understand as a > > Property and update the definitions and examples to leave it clear. > > > > Kind regards, > > > > > -- > Krzysztof Janowicz > > Geography Department, University of California, Santa Barbara > 4830 Ellison Hall, Santa Barbara, CA 93106-4060 > > Email: jano@geog.ucsb.edu > Webpage: http://geog.ucsb.edu/~jano/ > Semantic Web Journal: http://www.semantic-web-journal.net > > > > > > -- > > Krzysztof Janowicz > > > > Geography Department, University of California, Santa Barbara > > 4830 Ellison Hall, Santa Barbara, CA 93106-4060 > > > > Email: jano@geog.ucsb.edu > > Webpage: http://geog.ucsb.edu/~jano/ > > Semantic Web Journal: http://www.semantic-web-journal.net > >
Received on Monday, 8 May 2017 12:04:33 UTC