- From: Krzysztof Janowicz <janowicz@ucsb.edu>
- Date: Wed, 12 Oct 2016 09:20:14 -0700
- To: Kerry Taylor <kerry.taylor@anu.edu.au>, "Little, Chris" <chris.little@metoffice.gov.uk>, "Simon.Cox@csiro.au" <Simon.Cox@csiro.au>, "jlieberman@tumblingwalls.com" <jlieberman@tumblingwalls.com>
- Cc: "public-sdw-wg@w3.org" <public-sdw-wg@w3.org>
- Message-ID: <7f6d3371-9574-6cd9-cce2-aef0800a773d@ucsb.edu>
> As I now understand it now we need 3 different times to be attached > to an observation: stimulus time , phenomenon time (which is called > sampling time in ssn) , and observation result time. As stated before, I am fine with the 3 times. > An ssn:observation is ssn: observedby a ssn:sensor (which is very > similar or identical to a sensorml sensor). Are we ontologically > happy with the idea of a sensor observing a forecast? I can live with > it – I am no perfectionist. A ssn:sensor ssn:implements ssn:sensing > – and as sensing already admits algorithms – no problem here. And it > is backwardly-compatible. I think this is odd and the more we broaden the meaning of all these terms for the sake of being as inclusive as possible, the more we will lose meaning. This seems to be a very common problem/issue in ontology engineering. I would be in favor of introducing new concepts (such as forecast) instead of broadening existing concepts to a degree where they mean almost anything (and thus nothing). Best, Krzysztof On 10/12/2016 06:41 AM, Kerry Taylor wrote: > > As I now understand it now we need 3 different times to be attached > to an observation: stimulus time , phenomenon time (which is called > sampling time in ssn) , and observation result time. > > All of which need to be (optional) properties of a single > observation. Right? Ssn already has the latter two, but not the first. > > An ssn:observation is ssn: observedby a ssn:sensor (which is very > similar or identical to a sensorml sensor). Are we ontologically > happy with the idea of a sensor observing a forecast? I can live with > it – I am no perfectionist. A ssn:sensor ssn:implements ssn:sensing > – and as sensing already admits algorithms – no problem here. And it > is backwardly-compatible. > > Sensor in ssn: “A sensor can do (implements) sensing: that is, a > sensor is any entity that can follow a sensing method and thus observe > some Property of a FeatureOfInterest. Sensors may be physical devices, > computational methods, a laboratory setup with a person following a > method, or any other thing that can follow a Sensing Method to observe > a Property." > > How can a user be sure whether an observation is a forecast or a > measurement – by careful analysis of the various times attached --- is > that ok? Does it make a difference if the phenomenon time of the > forecast is already prior to current time? What if some are missing? > Should we care? > > I think we can do this. We would need one more property and we would > need to satisfy implementation requirements, to go in the standard. > > Maybe Josh and Chris could volunteer independent implementations you > have in the works? > > Alternatively we could add this as “non-normative” in the rec track > document (but it would probably have to sit in a different file > and/or namespace to the main ssn to do this --- we are still working > through those options). > > I have created issue-82 to track this identified need for a stimulus > time for forecast (which I don’t think btw is in our UCR!). > > This I think is entirely independent of the original ‘RE: SSN Thread > for github issue 378 - Side effects of ssn:Observation being a kind > of dul:Event instead of dul:Situation” as it works irrespective of > whether an observation is an act or a something else. > > --Kerry > > *From:*Little, Chris [mailto:chris.little@metoffice.gov.uk] > *Sent:* Wednesday, 12 October 2016 10:30 PM > *To:* Simon.Cox@csiro.au; Kerry Taylor <kerry.taylor@anu.edu.au>; > janowicz@ucsb.edu; jlieberman@tumblingwalls.com > *Cc:* maxime.lefrancois.86@gmail.com; public-sdw-wg@w3.org > *Subject:* RE: Forecasts and observations - was RE: SSN Thread for > github issue 378 - Side effects of ssn:Observation being a kind of > dul:Event instead of dul:Situation > > Dear all, > > I would just like to add my support for Simon and Rob’s posts. > > Over the last few years, numerous people, national and international > organisations have implemented O&M using the conceptual model for > forecasts/predictions as another type of observation – an estimate of > a value in the future. In particular, it has underpinned work in both > meteorology and aviation. > > These regulatory systems are likely to be in place for decades rather > than years. > > The prediction processes may be very heavyweight, using supercomputers > for a long time, may be manual (recording deviations from expected) or > may be lightweight, as in some automated instruments, such as > thermometers on radio-sondes, using their calibration profiles and > responsiveness/time lag parameters to actually provide a value > assigned to a fraction or a few seconds in the future! The radio sonde > is ascending at about 5m/sec, so the alignment of the temperature with > other observations on the balloon is critical. > > I hope we can maintain this continuum of > observations/estimates/predictions and deliver a compatible SSN by our > deadline. > > Chris > > *From:*Simon.Cox@csiro.au <mailto:Simon.Cox@csiro.au> > [mailto:Simon.Cox@csiro.au] > *Sent:* Monday, October 10, 2016 9:54 AM > *To:* kerry.taylor@anu.edu.au <mailto:kerry.taylor@anu.edu.au>; > janowicz@ucsb.edu <mailto:janowicz@ucsb.edu>; > jlieberman@tumblingwalls.com <mailto:jlieberman@tumblingwalls.com> > *Cc:* maxime.lefrancois.86@gmail.com > <mailto:maxime.lefrancois.86@gmail.com>; public-sdw-wg@w3.org > <mailto:public-sdw-wg@w3.org> > *Subject:* RE: Forecasts and observations - was RE: SSN Thread for > github issue 378 - Side effects of ssn:Observation being a kind of > dul:Event instead of dul:Situation > > Kerry – > > I think we are making progress here. Was not meaning to imply that > anyone was going to take their bat and go home, was only trying to lay > out the options. (BTW – while O&M v2.0 was officially published in > 2010 by OGC and 2011 by ISO, most of those definitions had been stable > through public drafts and earlier versions. Sorry if I confused things > by using ‘act’ and ‘activity’ as approximate synonyms. I guess the > former is a verb and the latter a noun?) > > As far as ‘sampling-time’ vs ‘phenomenon-time’ vs ‘stimulus-time’ > goes, the additional insight that emerged in the last week (thanks > Josh) is that the latter two are not necessarily the same! And that by > separating them we can indeed reconcile the various use-cases, in > particular allowing us to include forecasts and predictions alongside > the other cases. This is incredibly useful, and seems rather elegant. > But it does emphasize the need to be very careful in the terminology > and definitions. > > I’m watching all this carefully as you can tell, since there is a > scheduled review of ISO O&M due next year, so there is the opportunity > to bring all these things into alignment. The statutory world, who are > heavy users of O&M, also have an interest in terminological stability. > In this context, I should point out that the term ‘sampling-time’ is > already in the sampling-features part of O&M. It refers to the time > when the sample is created, which is not necessarily the same as > either the stimulus-time or phenomenon-time, so it would be preferable > if we could leave it there, and not see it used with inconsistent > semantics. > > I’m aware that this all does imply potentially renaming some > properties and clarifying some class definitions relative to what was > in the 2011 version of SSN, and I trust this is still on the table for > the SDWWG work, though it might push us into using a new RDF namespace. > > Simon > > *From:*Kerry Taylor [mailto:kerry.taylor@anu.edu.au] > *Sent:* Monday, 10 October 2016 1:50 PM > *To:* Cox, Simon (L&W, Clayton) <Simon.Cox@csiro.au > <mailto:Simon.Cox@csiro.au>>; janowicz@ucsb.edu > <mailto:janowicz@ucsb.edu>; jlieberman@tumblingwalls.com > <mailto:jlieberman@tumblingwalls.com> > *Cc:* maxime.lefrancois.86@gmail.com > <mailto:maxime.lefrancois.86@gmail.com>; public-sdw-wg@w3.org > <mailto:public-sdw-wg@w3.org> > *Subject:* RE: Forecasts and observations - was RE: SSN Thread for > github issue 378 - Side effects of ssn:Observation being a kind of > dul:Event instead of dul:Situation > > Sorry – to be more specific, following this suggestion, > > Øif the stimulus-time is omitted it is assumed to be the same as > phenomenon-time? > > I thought that, given ssn has both > http://www.w3.org/ns/ssn/observationSamplingTime (and noting its own > comment “Rebadged as phenomenon time in [O&M].”) and > http://www.w3.org/ns/ssn/observationResultTime then those two > properties are strictly enough. Are they? > > I favour the minimal change approach only so that we can actually get > to a result. > > Adding one more property, if that solves it, also seems possible > provided we can get suitable implementations. Can we? I have no > resources to volunteer that but some others do. Changing rdfs:comment > stuff, especially when only broadening, I expect (unconfirmed!) we > can get away without needing new implementations at all. Changing the > name of existing ssn terms to something else we certainly cannot do > without implementations and close attention. How will that > implementation be achieved? > > ØMaybe the issue is around whether we consider this a ‘sensor’ > ontology (indeed, that is in the SSN name) or an ‘observation’ > ontology. If it is narrowly the former, then those of us interested in > the more general case may have to go elsewhere. But I thought the > group (and the UCR) was comfortable with dealing with ‘observations’. > > As you know, ssn already covers observations at least reasonably > well. Arguably not perfectly. If it is not good enough then “then > those of us interested in the more general case” have every right to > work with SDW to make it better. Why not? The only reason for why > not could be actually failing to deliver. And we have a plan to > deliver a non-rec track alignment to O&M anyway (see FPWD) --- there > is no reason I can think of (other than resources/effort) to deliver > that and without the same implementation and oversight requirements. > > Alternatively, we can follow Rob’s suggestion of taking some of the > perfect out of the standardisation discussion and parking it as a > note. No implementations required. Suits me well enough. I admit, I > would certainly prefer to deliver the > “scope/usefulness/completeness/consistency of its content” in the rec > track but that seems to be vanishingly unlikely at this stage. > > I had hoped the O&M alignment (and btw the DUL alignment too, and > critically importantly perhaps the SOSA-core alignment is forced to go > there too) )would go in rec track doc as non-normative -- some > people would have missed that discussion at the F2F. I will remind > Phil to check our options here. Alternatively this could be (should > be?) the same Note that Rob is suggesting. > > And another apology – I really wanted to talk through these options > and test our implementation capability at the last ssn meeting, but it > got sidelined. With one objection (not sure it was a -1 though) , I > heard that the group confirmed that we intend to publish a standard. > Right now we have very, very little progress to show towards the > really necessary components for that goal. > > -Kerry > > *From:*Simon.Cox@csiro.au <mailto:Simon.Cox@csiro.au> > [mailto:Simon.Cox@csiro.au] > *Sent:* Monday, 10 October 2016 9:54 AM > *To:* Kerry Taylor <kerry.taylor@anu.edu.au > <mailto:kerry.taylor@anu.edu.au>>; janowicz@ucsb.edu > <mailto:janowicz@ucsb.edu>; jlieberman@tumblingwalls.com > <mailto:jlieberman@tumblingwalls.com> > *Cc:* maxime.lefrancois.86@gmail.com > <mailto:maxime.lefrancois.86@gmail.com>; public-sdw-wg@w3.org > <mailto:public-sdw-wg@w3.org> > *Subject:* Forecasts and observations - was RE: SSN Thread for github > issue 378 - Side effects of ssn:Observation being a kind of dul:Event > instead of dul:Situation > > ØAnd btw this cannot be done if an ssn:observation becomes an “act”. > > I don’t understand this comment. > > The ‘act-ness’ of observation is emerges from the ‘result-time’ > property – this was why result-time was included in O&M, and why it is > distinct from phenomenon-time (the time the value applies in the world). > > Josh’s proposal (i.e. to also add a “stimulus-time” property) appears > to reconcile all the requirements. A prediction or forecast is merely > an observation whose stimulus time is usually prior to but may be > contemporary with the result-time, and is prior to the > phenomenon-time. The temporal logic is key, but requires multiple > time properties. > > Øthe only challenge I foresee is whether we can feel comfortable with > the idea that a sensor ontology also sneaks forecasting in, and that > “Sensing” includes forecasting and that a “sensor” implements > forecasting. > > Maybe the issue is around whether we consider this a ‘sensor’ ontology > (indeed, that is in the SSN name) or an ‘observation’ ontology. If it > is narrowly the former, then those of us interested in the more > general case may have to go elsewhere. But I thought the group (and > the UCR) was comfortable with dealing with ‘observations’. > > Simon > > *From:*Kerry Taylor [mailto:kerry.taylor@anu.edu.au] > *Sent:* Sunday, 9 October 2016 12:35 PM > *To:* Kerry Taylor <kerry.taylor@anu.edu.au > <mailto:kerry.taylor@anu.edu.au>>; janowicz@ucsb.edu > <mailto:janowicz@ucsb.edu>; Cox, Simon (L&W, Clayton) > <Simon.Cox@csiro.au <mailto:Simon.Cox@csiro.au>>; > jlieberman@tumblingwalls.com <mailto:jlieberman@tumblingwalls.com> > *Cc:* maxime.lefrancois.86@gmail.com > <mailto:maxime.lefrancois.86@gmail.com>; public-sdw-wg@w3.org > <mailto:public-sdw-wg@w3.org> > *Subject:* RE: SSN Thread for github issue 378 - Side effects of > ssn:Observation being a kind of dul:Event instead of dul:Situation > > Btw, this discussion is a little confused. SSN has only an > “observationResulttime” and an “observationSamplingtime”, copied here > below. Simply expanding the scope of “ssn:observationSamplingTime” > to include a stimulus might be an easy, very low impact, way to > achieve this goal, if I understand it? > > I **think** josh’s goal to > > >Is a prediction just another procedure within an observation, or is a > prediction a different type of event (e.g. a model run) that generates > an imaginary / potential observation? > > Can also be achieved by the simple trick of changing the textual > description of an ssn:observation, and a few other terms, with no > nasty effect on backward compatibility – the only challenge I foresee > is whether we can feel comfortable with the idea that a sensor > ontology also sneaks forecasting in, and that “Sensing” includes > forecasting and that a “sensor” implements forecasting. Not really our > business? > > And btw this cannot be done if an ssn:observation becomes an “act”. > > -Kerry > > ### http://www.w3.org/ns/ssn/observationResultTime > > ssn:observationResultTime rdf:type owl:ObjectProperty ; > > dc:source "http://www.opengeospatial.org/standards/om" ; > > rdfs:comment "The result time is the time when the procedure > associated with the observation act was applied." , > > "The result time shall describe the time when the result became > available, typically when the procedure associated with the > observation was completed For some observations this is identical to > the phenomenonTime. However, there are important cases where they > differ.[O&M]" ; > > rdfs:isDefinedBy "http://www.w3.org/ns/ssn" ; > > rdfs:label "observation result time" ; > > rdfs:seeAlso > "http://www.w3.org/2005/Incubator/ssn/wiki/SSN_Observation#Observation" . > > ### http://www.w3.org/ns/ssn/observationSamplingTime > > ssn:observationSamplingTime rdf:type owl:ObjectProperty ; > > dc:source "http://www.opengeospatial.org/standards/om" ; > > rdfs:comment "Rebadged as phenomenon time in [O&M]. The phenomenon > time shall describe the time that the result applies to the property > of the feature-of-interest. This is often the time of interaction by a > sampling procedure or observation procedure with a real-world feature." , > > "The sampling time is the time that the result applies to the > feature-of-interest. This is the time usually required for geospatial > analysis of the result." ; > > rdfs:isDefinedBy "http://www.w3.org/ns/ssn" ; > > rdfs:label "observation sampling time" ; > > rdfs:seeAlso > "http://www.w3.org/2005/Incubator/ssn/wiki/SSN_Observation#Observation" . > > *From:*Kerry Taylor [mailto:kerry.taylor@anu.edu.au] > *Sent:* Sunday, 9 October 2016 11:56 AM > *To:* janowicz@ucsb.edu <mailto:janowicz@ucsb.edu>; Simon.Cox@csiro.au > <mailto:Simon.Cox@csiro.au>; jlieberman@tumblingwalls.com > <mailto:jlieberman@tumblingwalls.com> > *Cc:* maxime.lefrancois.86@gmail.com > <mailto:maxime.lefrancois.86@gmail.com>; public-sdw-wg@w3.org > <mailto:public-sdw-wg@w3.org> > *Subject:* RE: SSN Thread for github issue 378 - Side effects of > ssn:Observation being a kind of dul:Event instead of dul:Situation > > AFAIK we **can** introduce changes to ssn. But we MUST be > backward-compatible (see recent info on namespaces, purl and > implementations from Phil > https://lists.w3.org/Archives/Public/public-sdw-wg/2016Oct/0024.html). > And we MUST have implementations. Here, we are now proposing to > introduce a new incompatibility with the O&M spec, aren’t we? I am > ok with that, but then what are we doing on the other hand changing > ssn:Observation to be an activity/event/act *only* because it makes > it more compatible with the O&M spec? The very same O&M spec we are > now proposing to move away from here? What**are we doing? > > Personally, I would be very happy with this proposal as long as I can > believe that implementations will appear in our timeframe and that the > effect on other aspects of ssn is both clearly articulated and minimal > and also demonstrated by multiple implementations. This should be our > bar for every change to ssn. Personally, I am happy to give up on > compatibility with the O&M spec. We might possibly expect the O&M > spec to be revised to be closer to what we are doing here. > > Kerry > > *From:*Krzysztof Janowicz [mailto:janowicz@ucsb.edu] > *Sent:* Sunday, 9 October 2016 7:50 AM > *To:* Simon.Cox@csiro.au <mailto:Simon.Cox@csiro.au>; > jlieberman@tumblingwalls.com <mailto:jlieberman@tumblingwalls.com> > *Cc:* Kerry Taylor <kerry.taylor@anu.edu.au > <mailto:kerry.taylor@anu.edu.au>>; maxime.lefrancois.86@gmail.com > <mailto:maxime.lefrancois.86@gmail.com>; public-sdw-wg@w3.org > <mailto:public-sdw-wg@w3.org> > *Subject:* Re: SSN Thread for github issue 378 - Side effects of > ssn:Observation being a kind of dul:Event instead of dul:Situation > > I like that. I think it addresses my original concern nicely. > > Though I think I would adjust the naming to ‘stimulusTime’ vs > ‘phenomenonTime’ (the latter is still the time that most users > care about and preserves the current semantics). > > if the stimulus-time is omitted it is assumed to be the same as > phenomenon-time? > > > I like the idea as well. But where is this all going a revised SSN? So > are we introducing changes after all? > > 1) I think you mean manometer, which depends on the density of > mercury, not its compressibility. Different stimulus. > > > Thanks. > > > > On 10/06/2016 11:50 PM, Simon.Cox@csiro.au <mailto:Simon.Cox@csiro.au> > wrote: > > I like that. I think it addresses my original concern nicely. > > Though I think I would adjust the naming to ‘stimulusTime’ vs > ‘phenomenonTime’ (the latter is still the time that most users > care about and preserves the current semantics). > > if the stimulus-time is omitted it is assumed to be the same as > phenomenon-time? > > *From:*Joshua Lieberman [mailto:jlieberman@tumblingwalls.com] > *Sent:* Thursday, 6 October 2016 9:02 PM > *To:* janowicz@ucsb.edu <mailto:janowicz@ucsb.edu> > *Cc:* Cox, Simon (L&W, Clayton) <Simon.Cox@csiro.au> > <mailto:Simon.Cox@csiro.au>; kerry.taylor@anu.edu.au > <mailto:kerry.taylor@anu.edu.au>; maxime.lefrancois.86@gmail.com > <mailto:maxime.lefrancois.86@gmail.com>; public-sdw-wg@w3.org > <mailto:public-sdw-wg@w3.org> > *Subject:* Re: SSN Thread for github issue 378 - Side effects of > ssn:Observation being a kind of dul:Event instead of dul:Situation > > Jano, > > 1) I think you mean manometer, which depends on the density of > mercury, not its compressibility. Different stimulus. > > 2) As long as it is clear that the stimulus time has to overlap > the measurement time at least in part. > > 3) Pondering further, I think it makes more sense for a prediction > to estimate an observable property in the future based on present > stimulus / stimuli (related to that property by a model). This > does carry the implication that some other, more contemporaneous > stimulus would also occur in the future if appropriate, but that > stimulus would not be a result of the predictive observation. > Instead it would be the stimulus for another observation that also > takes place in the future and results in another, validating > estimate of the observable property. This should work pretty well > to represent both present and future estimates, however, it will > take some elaboration of the time parameters, namely > differentiation of PhenomenonTime from ObservablePropertyTime. > > Josh > > On Oct 5, 2016, at 5:46 PM, Krzysztof Janowicz > <janowicz@ucsb.edu <mailto:janowicz@ucsb.edu>> wrote: > > IMHO, /Stimulus/ is best conceptualized as detectable changes > in the environment that trigger the observation process. In > 2010 (for the SSO) Michael and I wrote: > > "Stimuli are detectable changes in the environment, i.e., in > the physical world. They are the starting point of each > measurement as they act as triggers for sensors. Stimuli can > either be directly or indirectly related to observable > properties and, therefore, to features of interest. They can > also be actively produced by a sensor to perform observations. > The same types of stimulus can trigger different kinds of > sensors and be used to reason about different properties. > Nevertheless, a stimulus may only be usable as proxy for a > specific region of an observed property. Examples for stimuli > include the expansion of liquids or sound waves emitted by a > sonar. The expansion of mercury can be used to draw > conclusions about the temperature of a surface that is in > close contact. While the expansion is unspecific with respect > to the kind of surface, e.g., water versus skin, the usage as > stimulus is limited by its melting and boiling points. > Moreover, mercury is not restricted to thermometers but e.g., > also used in nanometers. Note, that the stimulus is the > expansion of mercury, not mercury as such.” > > 1) > > > The last sentence (and assuming this definition is still > valid/acceptable for our current work), is the most important > one. A stimulus is an event (if we really, really, really want > to use these terms). The stimulus also has to start before the > observation can take place. Multiple possible temporal > relations can hold between the two. for instance, the mercury > in the text above will shrink after an measurement procedure > (resulting in an observation) is executed. This will (or will > not) keep triggering a sensor but we stopped caring because we > arrived at the observation we anted to archive. > > 2) > > > I like Josh's idea about predicting future stimuli but would > suggest not to mix this with the notion of an observation. > Predictions about the future are not observations in the sense > we use in the SSN; if they are, they are predictions based on > observations which in turn are based on stimuli that we > consider good proxies for the stimulus we want to predict :-). > > 3) > > > Best, > Jano > > > > On 10/03/2016 08:36 PM, Joshua Lieberman wrote: > > I do mean (topologically not logically) disjoint in time, > i.e. non-overlapping. If “isPostConditionOf” carries a > strict temporal meaning, then it breaks the relationship > between stimulus and observation. You can’t measure a > temperature if the temperature has gone away before you > measure it. If the meaning is only consequential, in the > sense of observation O→stimulus S, then it would be a > reasonable predicate. Still tricky for prediction, i.e. to > assert that a stimulus in the future is a consequence of a > prediction in the present. I suppose one could indicate in > some way that it's a weaker consequence. > > One could also argue that an observation that overlaps its > stimulus in time is a measurement, while an observation > that doesn’t overlap its stimulus is a prediction. A model > procedure can predict the past, the present, or the > future, or none of the above if the model conditions are > hypothetical. It is going to require some more thought, > though, to figure out how to apply the SSN / O&M terms to > this situation. Is a prediction just another procedure > within an observation, or is a prediction a different type > of event (e.g. a model run) that generates an imaginary / > potential observation? > > —Josh > > On Oct 3, 2016, at 1:31 PM, simon.cox@csiro.au > <mailto:simon.cox@csiro.au> wrote: > > Weighing in maybe a little late: > > One of the motivations for the term ‘result’ in O&M > was clarification of the post-condition of the > observation, understood as an event. > > And (as Josh has pointed out) the concepts of > phenomenon-time and result-time were also a part of > this story. But O&M also included interpretation, > numerical modelling, and forecasting (i.e. when the > phenomenon-time is later than the result-time), so we > need to be careful here. Perhaps there is a useful > taxonomy of observation types on the basis of the > relationship between stimuls/phenomenon-time/result-time … > > The notion of ‘stimulus’ was a very important > contribution from SSN - George Percivall was on my > case about this early in the story of SWE, but it > didn’t get formalized in the O&M model. But while it > is relatively straightforward how it applies to the > classical notion of sensing, I need some help to > understand what the ‘stimulus’ is for a forecast. > > Simon > > *From:*Kerry Taylor [mailto:kerry.taylor@anu.edu.au] > *Sent:*Monday, 3 October 2016 5:05 PM > *To:*Joshua Lieberman <jlieberman@tumblingwalls.com > <mailto:jlieberman@tumblingwalls.com>> > *Cc:*Maxime Lefrançois <maxime.lefrancois.86@gmail.com > <mailto:maxime.lefrancois.86@gmail.com>>; SDW WG > Public List <public-sdw-wg@w3.org > <mailto:public-sdw-wg@w3.org>> > *Subject:*RE: SSN Thread for github issue 378 - Side > effects of ssn:Observation being a kind of dul:Event > instead of dul:Situation > > Hi Josh, > > I am not sure I follow – because I am not clear what > you mean by “disjoint” here. For me, I meant it as > “something cannot be both of those things”, > > but perhaps you mean something about non-overlapping > time intervals? > > If we can’t live with “isPostconditionOf” (and I > cannot find any other alternative in dolce myself, but > I would be very grateful if someone can) then I can > see only 3 other options. > > 1) is to disconnect the observation from the stimulus > – which seems pretty dumb to me and if so then I > would suggest we go even further and just drop > stimulus entirely ( or it could remain connected to a > sensor, but if a sensor could respond to multiple > stimuli we would have no idea which one provoked this > observation. Which gives another option I suppose – > insist that each sensor can have at most one stimulus > and then the stimulus could be retrived with the > observation by following the sensor – but this is yet > another change). > > 2) Make up a new term in ssn for the purpose --- but I > am not keen to introduce new terms without a really > strong reason. > > 3)Make up a new term in the alignment (in a new > namespace) but not in ssn proper --- I can’t see much > value in that for anyone. > > I think I can live with “isPostconditionOf” > > Maxime, did you spot any other problems with changing > observation this way? > > --Kerry > > *From:*Joshua Lieberman > [mailto:jlieberman@tumblingwalls.com] > *Sent:*Thursday, 29 September 2016 3:59 AM > *To:*Kerry Taylor <kerry.taylor@anu.edu.au > <mailto:kerry.taylor@anu.edu.au>> > *Cc:*Maxime Lefrançois <maxime.lefrancois.86@gmail.com > <mailto:maxime.lefrancois.86@gmail.com>>; SDW WG > Public List <public-sdw-wg@w3.org > <mailto:public-sdw-wg@w3.org>> > *Subject:*Re: SSN Thread for github issue 378 - Side > effects of ssn:Observation being a kind of dul:Event > instead of dul:Situation > > This seems to be another consequence of the > distinction between Observation as record and > Observation as event. It makes sense that a record be > disjoint with and later in time than a Stimulus > (ResultTime vs PhenomenonTime) but if the event of > sensing is disjoint with the Stimulus being sensed, > there generally isn’t going to be any result. > Therefore, if om:Observation is to be adopted, > isPostconditionOf will not be the appropriate > relationship between Stimulus and Observation. > > —Josh > > On Sep 28, 2016, at 9:23 AM, Kerry Taylor > <kerry.taylor@anu.edu.au > <mailto:kerry.taylor@anu.edu.au>> wrote: > > Maxime, > > Thank you so much for following up on this. > > isPostconditionOf looks ok to me because > > -(1) its rdfs:comment annotation says “ Direct > succession applied to situations. E.g., 'Taking > some rest is a postcondition of my search for a > hotel'.” > > -(2) and another reference says ‘"Direct > succession applied to situations. E.g., 'A > postcondition of our Plan is to have things > settled'."” > > -(3) it seems to capture the intended relationship > between a stimulus event and an observation. > Certainly we would not want that a stimulus causes > an observation, nor that an observation is a > necessary consequence of a stimulus, but I think > we are ok here. It does say that the stimulus > comes first, and then the observation, but that > seems quite ok too. > > Note that the domain and range of > isPostconditionOf are both the union of Event and > Situation, so no problem there. includesEvent had > a range of Event, so this expansion of the range > to Event or Situation is not going to get > existing implementations in to additional trouble > (ie beyond the trouble already implied by the > descision to change Observation). > > It is a subproperty of directlyFollows (an > intransitive ordering relation) and an inverse of > hasPostcondition. While these may not have been > intended by the original includesEvent (in which > the situation of observation just includes the > Stimulus event), I cannot see any problem in > using isPostconditionOf, and indeed it looks to me > like the difference in meaning is only the > necessary difference that arises to the move of > Observation to an Event. > > So I’d vote for isPostconditionOf, being the > closest match possible to the previous. > > --Kerry > > *From:*Maxime Lefrançois > [mailto:maxime.lefrancois.86@gmail.com] > *Sent:*Wednesday, 28 September 2016 6:53 PM > *To:*SDW WG Public List <public-sdw-wg@w3.org > <mailto:public-sdw-wg@w3.org>> > *Subject:*SSN Thread for github issue 378 - Side > effects of ssn:Observation being a kind of > dul:Event instead of dul:Situation > > Dear all, > > If each github issue shall have its own thread on > the SDW list, this is the one for issue 378 - > https://github.com/w3c/sdw/issues/378 : > > if|ssn:Observation| > <http://www.w3.org/ns/ssn/Observation>is a kind > of|dul:Event| > <http://www.ontologydesignpatterns.org/ont/dul/DUL.owl#Event>instead > of a|dul:Situation| > > there is an immediate side effect to resolve: > > /axiom:/ > > |ssn:Observation rdfs:subClassOf [ owl:onProperty > dul:includesEvent ; owl:someValuesFrom > ssn:Stimulus ] .| > > /context axioms:/ > > |ssn:Stimulus rdfs:subClassOf dul:Event .| > > |dul:includesEvent rdfs:domain dul:Situation ; > rdfs:range dul:Event .| > > /solution to solve the side effect:/ > > replace the mention of|dul:includesEvent|in axiom > by a property that has for domain and range|dul:Event| > > the only such DUL properties > are:|dul:isPreconditionOf|, > and|dul:isPostconditionOf|. > > Neither of them seem to fit, > so, should this axiom be simply deleted from the > SSN-DUL alignment ? > > Kind regards > > Maxime Lefrançois > > -- > > Krzysztof Janowicz > > > > Geography Department, University of California, Santa Barbara > > 4830 Ellison Hall, Santa Barbara, CA 93106-4060 > > > > Email:jano@geog.ucsb.edu <mailto:jano@geog.ucsb.edu> > > Webpage:http://geog.ucsb.edu/~jano/ <http://geog.ucsb.edu/%7Ejano/> > > Semantic Web Journal:http://www.semantic-web-journal.net > <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 <mailto:jano@geog.ucsb.edu> > Webpage:http://geog.ucsb.edu/~jano/ <http://geog.ucsb.edu/%7Ejano/> > 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 Wednesday, 12 October 2016 16:20:51 UTC