Re: [Wikidata-l] Subclass of/instance of
On Thu, May 15, 2014 at 5:03 PM, Markus Krötzsch mar...@semantic-mediawiki.org wrote: I applaud your comparison of inferencing with a form of decompression. I think this is a nice intuition (in fact, some people have researched semantic compression where one tries to reduce the size of a knowledge base by eliminating things that follow from the rest anyway). Markus, sorry the delay answering to this, I had to let the ideas grow for a while. I also like the idea of decompression, that is what makes your database of inferred data even more useful. There is a lot of data that can be inferred, and not just from following the relationships, but by computing. For instance population density which can be calculated from area and population, or aggregates of the population of each town in a district. Another source of inferred statements are wp categories. Most of them are very easily translatable into statements, and the other way round too. A place where to store and process these inferences would be most useful if WD is not the right place. You also say: Constraints are a great start. We should now ask how we could improve the management of constraints in the future, and which constraints we will have then. The first step will be having them as statements, then having them as queries, and finally automating their correction, either by semi-automatic tools, or with gamification. How to automatically transform a constraint into a game to solve the outliers it might be also an interesting topic. And of course, more far fetched, but nevertheless relevant is how to connect the property to a perceptual mechanism. About improving the reliability: yes, as wikidata grows bigger some statements become more important. There is something to be learnt about how neural nets work, specially strengthening most-used (or traveled, or accepted, or viewed) connections. Another process little understood now is the need to forget, or in wikidata terms auto-deprecate information that is no longer current. Not very relevant now, but something to keep in mind for the next years. Cheers, Micru ___ Wikidata-l mailing list Wikidata-l@lists.wikimedia.org https://lists.wikimedia.org/mailman/listinfo/wikidata-l
Re: [Wikidata-l] Subclass of/instance of
On 14/05/14 19:33, Joe Filceolaire wrote: Except that there are lots of people who have appeared in one movie who don't consider themselves actors and should not have the 'occupation=actor/actress'. There are good reasons for some constraints to be gadgets that can be overridden rather than hard coded semantic limits. Sure, we completely agree here. It was just an example. But it shows why we need any such feature to be controlled by the community ;-) I do think we should be able to have hard coded reverse properties and symmettric properties. By hard coded do you mean stored explicitly (as opposed to: inferred in some way)? It will always be possible to store anything explicitly in this sense (but I guess you know this; maybe I misunderstood what you said; feel free to clarify). In general, what I mentioned about inferencing is not supposed to alter the way in which the site works. It would be more like a layer on top that could be useful for asking queries. For example, imagine you want to query for the grandmother of a person: we don't have this property in Wikidata but we have enough information to answer the query. So you would have to research how to get this information by combining existing properties. The idea is that one could have a place to keep this information (= the definition of grandmother in terms of Wikidata properties). We would then have a community approved way of finding grandmothers in Wikidata, and you would be much faster with your query. At the same time, you could look up the definition to find out how Wikidata really stores this information. None of this would would change how the underlying data works, but it could contribute to some data modelling problems because it gives you an option to support a property without the added maintenance cost on the data management level. Cheers, Markus On Wed, May 14, 2014 at 2:33 PM, Markus Krötzsch mar...@semantic-mediawiki.org mailto:mar...@semantic-mediawiki.org wrote: I guess there is already a group of people who deal w Hi Eric, Thanks for all the information. This was very helpful. I only get to answer now since we have been quite busy building RDF exports for Wikidata (and writing a paper about it). I will soon announce this here (we still need to fix a few details). You were asking about using these properties like rdfs:subClassOf and rdf:type. I think that's entirely possible, since the modelling is very reasonable and would probably yield good results. Our reasoner ELK could easily handle the class hierarchy in terms of size, but you don't really need such a highly optimized tool for this as long as you only have subClassOf. In fact, the page you linked to shows that it is perfectly possible to compute the class hierarchy with Wikidata Query and to display all of it on one page. ELK's main task is to compute class hierarchies for more complicated ontologies, which we do not have yet. OTOH, query answering and data access are different tasks that ELK is not really intended for (although it could do some of this as well). Regarding future perspectives: one thing that we have also done is to extract OWL axioms from property constraint templates on Wikidata talk pages (we will publish the result soon, when announcing the rest). This gives you only some specific types of OWL axioms, but it is making things a bit more interesting already. In particular, there are some constraints that tell you that an item should have a certain class, so this is something you could reason with. However, the current property constraint system does not work too well for stating axioms that are not related to a particular property (such as: Every [instance of] person who appears as an actor in some film should be [instance of] in the class 'actor' -- which property or item page should this be stated on?). But the constraints show that it makes sense to express such information somehow. In the end, however, the real use of OWL (and similar ontology languages) is to remove the need for making everything explicit. That is, instead of constraints (which say: if your data looks like X, then your data should also include Y) you have axioms (which say: if your data looks like X, then Y follows automatically). So this allows you to remove redundancy rather than to detect omissions. This would make more sense with derived notions that one does not want to store in the database, but which make sense for queries (like grandmother). One would need a bit more infrastructure for this; in particular, one would need to define grandmother (with labels in many languages) even if one does not want to use it as a property but only in queries. Maybe one could have a separate Wikibase installation for defining such derived notions without needing
Re: [Wikidata-l] Subclass of/instance of
Hi Eric, Thanks for all the information. This was very helpful. I only get to answer now since we have been quite busy building RDF exports for Wikidata (and writing a paper about it). I will soon announce this here (we still need to fix a few details). You were asking about using these properties like rdfs:subClassOf and rdf:type. I think that's entirely possible, since the modelling is very reasonable and would probably yield good results. Our reasoner ELK could easily handle the class hierarchy in terms of size, but you don't really need such a highly optimized tool for this as long as you only have subClassOf. In fact, the page you linked to shows that it is perfectly possible to compute the class hierarchy with Wikidata Query and to display all of it on one page. ELK's main task is to compute class hierarchies for more complicated ontologies, which we do not have yet. OTOH, query answering and data access are different tasks that ELK is not really intended for (although it could do some of this as well). Regarding future perspectives: one thing that we have also done is to extract OWL axioms from property constraint templates on Wikidata talk pages (we will publish the result soon, when announcing the rest). This gives you only some specific types of OWL axioms, but it is making things a bit more interesting already. In particular, there are some constraints that tell you that an item should have a certain class, so this is something you could reason with. However, the current property constraint system does not work too well for stating axioms that are not related to a particular property (such as: Every [instance of] person who appears as an actor in some film should be [instance of] in the class 'actor' -- which property or item page should this be stated on?). But the constraints show that it makes sense to express such information somehow. In the end, however, the real use of OWL (and similar ontology languages) is to remove the need for making everything explicit. That is, instead of constraints (which say: if your data looks like X, then your data should also include Y) you have axioms (which say: if your data looks like X, then Y follows automatically). So this allows you to remove redundancy rather than to detect omissions. This would make more sense with derived notions that one does not want to store in the database, but which make sense for queries (like grandmother). One would need a bit more infrastructure for this; in particular, one would need to define grandmother (with labels in many languages) even if one does not want to use it as a property but only in queries. Maybe one could have a separate Wikibase installation for defining such derived notions without needing to change Wikidata? There are no statements on properties yet, but one could also use item pages to define derived properties when using another site ... Best regards, Markus P.S. Thanks for all the work on the semantic modelling aspects of Wikidata. I have seen that you have done a lot in the discussions to clarify things there. On 06/05/14 04:53, emw wrote: Hi Markus, You asked who is creating all these [subclass of] statements and how is this done? The class hierarchy in http://tools.wmflabs.org/wikidata-todo/tree.html?q=Q35120rp=279lang=en shows a few relatively large subclass trees for specialist domains, including molecular biology and mineralogy. The several thousand subclass of 'gene' and 'protein' subclass claims were created by members of WikiProject Molecular biology (WD:MB), based on discussions in [1] and [2]. The decision to use P279 instead of P31 there was based on the fact that the is-a relation in Gene Ontology maps to rdfs:subClassOf, which P279 is based on. The claims were added by a bot [3], with input from WD:MB members. The data ultimately comes from external biological databases. A glance at the mineralogy class hierarchy indicates it has been constructed by WikiProject Mineralogy [4] members through non-bot edits. I imagine most of the other subclass of claims are done manually or semi-automatically outside specific Wikiproject efforts. In other words, I think most of the other P279 claims are added by Wikidata users going into the UI and building usually-reasonable concept hierarchies on domains they're interested in. I've worked on constructing class hierarchies for health problems (e.g. diseases and injuries) [5] and medical procedures [6] based on classifications like ICD-10 and assertions and templates on Wikipedia (e.g. [8]). It's not incredibly surprising to me that Wikidata has about 36,000 subclass of (P279) claims [9]. The property has been around for over a year and is a regular topic of discussion [10] along with instance of (P31), which has over 6,600,000 claims. You noted a dubious claim subclass of claim for 'House of Staufen' (Q130875). I agree that instance of would probably be the better membership property
Re: [Wikidata-l] Subclass of/instance of
Except that there are lots of people who have appeared in one movie who don't consider themselves actors and should not have the 'occupation=actor/actress'. There are good reasons for some constraints to be gadgets that can be overridden rather than hard coded semantic limits. I do think we should be able to have hard coded reverse properties and symmettric properties. Joe filceolaire On Wed, May 14, 2014 at 2:33 PM, Markus Krötzsch mar...@semantic-mediawiki.org wrote: Hi Eric, Thanks for all the information. This was very helpful. I only get to answer now since we have been quite busy building RDF exports for Wikidata (and writing a paper about it). I will soon announce this here (we still need to fix a few details). You were asking about using these properties like rdfs:subClassOf and rdf:type. I think that's entirely possible, since the modelling is very reasonable and would probably yield good results. Our reasoner ELK could easily handle the class hierarchy in terms of size, but you don't really need such a highly optimized tool for this as long as you only have subClassOf. In fact, the page you linked to shows that it is perfectly possible to compute the class hierarchy with Wikidata Query and to display all of it on one page. ELK's main task is to compute class hierarchies for more complicated ontologies, which we do not have yet. OTOH, query answering and data access are different tasks that ELK is not really intended for (although it could do some of this as well). Regarding future perspectives: one thing that we have also done is to extract OWL axioms from property constraint templates on Wikidata talk pages (we will publish the result soon, when announcing the rest). This gives you only some specific types of OWL axioms, but it is making things a bit more interesting already. In particular, there are some constraints that tell you that an item should have a certain class, so this is something you could reason with. However, the current property constraint system does not work too well for stating axioms that are not related to a particular property (such as: Every [instance of] person who appears as an actor in some film should be [instance of] in the class 'actor' -- which property or item page should this be stated on?). But the constraints show that it makes sense to express such information somehow. In the end, however, the real use of OWL (and similar ontology languages) is to remove the need for making everything explicit. That is, instead of constraints (which say: if your data looks like X, then your data should also include Y) you have axioms (which say: if your data looks like X, then Y follows automatically). So this allows you to remove redundancy rather than to detect omissions. This would make more sense with derived notions that one does not want to store in the database, but which make sense for queries (like grandmother). One would need a bit more infrastructure for this; in particular, one would need to define grandmother (with labels in many languages) even if one does not want to use it as a property but only in queries. Maybe one could have a separate Wikibase installation for defining such derived notions without needing to change Wikidata? There are no statements on properties yet, but one could also use item pages to define derived properties when using another site ... Best regards, Markus P.S. Thanks for all the work on the semantic modelling aspects of Wikidata. I have seen that you have done a lot in the discussions to clarify things there. On 06/05/14 04:53, emw wrote: Hi Markus, You asked who is creating all these [subclass of] statements and how is this done? The class hierarchy in http://tools.wmflabs.org/wikidata-todo/tree.html?q=Q35120rp=279lang=en shows a few relatively large subclass trees for specialist domains, including molecular biology and mineralogy. The several thousand subclass of 'gene' and 'protein' subclass claims were created by members of WikiProject Molecular biology (WD:MB), based on discussions in [1] and [2]. The decision to use P279 instead of P31 there was based on the fact that the is-a relation in Gene Ontology maps to rdfs:subClassOf, which P279 is based on. The claims were added by a bot [3], with input from WD:MB members. The data ultimately comes from external biological databases. A glance at the mineralogy class hierarchy indicates it has been constructed by WikiProject Mineralogy [4] members through non-bot edits. I imagine most of the other subclass of claims are done manually or semi-automatically outside specific Wikiproject efforts. In other words, I think most of the other P279 claims are added by Wikidata users going into the UI and building usually-reasonable concept hierarchies on domains they're interested in. I've worked on constructing class hierarchies for health problems (e.g. diseases and injuries) [5] and medical
Re: [Wikidata-l] Subclass of/instance of
Hi Markus, You asked who is creating all these [subclass of] statements and how is this done? The class hierarchy in http://tools.wmflabs.org/wikidata-todo/tree.html?q=Q35120rp=279lang=enshows a few relatively large subclass trees for specialist domains, including molecular biology and mineralogy. The several thousand subclass of 'gene' and 'protein' subclass claims were created by members of WikiProject Molecular biology (WD:MB), based on discussions in [1] and [2]. The decision to use P279 instead of P31 there was based on the fact that the is-a relation in Gene Ontology maps to rdfs:subClassOf, which P279 is based on. The claims were added by a bot [3], with input from WD:MB members. The data ultimately comes from external biological databases. A glance at the mineralogy class hierarchy indicates it has been constructed by WikiProject Mineralogy [4] members through non-bot edits. I imagine most of the other subclass of claims are done manually or semi-automatically outside specific Wikiproject efforts. In other words, I think most of the other P279 claims are added by Wikidata users going into the UI and building usually-reasonable concept hierarchies on domains they're interested in. I've worked on constructing class hierarchies for health problems (e.g. diseases and injuries) [5] and medical procedures [6] based on classifications like ICD-10 and assertions and templates on Wikipedia (e.g. [8]). It's not incredibly surprising to me that Wikidata has about 36,000 subclass of (P279) claims [9]. The property has been around for over a year and is a regular topic of discussion [10] along with instance of (P31), which has over 6,600,000 claims. You noted a dubious claim subclass of claim for 'House of Staufen' (Q130875). I agree that instance of would probably be the better membership property to use there. Such questionable usage of P279 is probably uncommon, but definitely not singular. The dynasty class hierarchy shows 13 dubious cases at the moment [11]. I would guess less than 5% of subclass of claims have that kind of issue, where instance of would make more sense. I think there are probably vastly more cases of the converse: instance of being used where subclass of would make more sense. As you probably know, P31 and P279 are intended to have the semantics of rdf:type and rdfs:subClassOf per community decision. A while ago I read a bit about the ELK reasoner you were involved with [12], which makes use of the seemingly class-centric OWL EL profile. Do you have any plans to integrate features of ELK with the Wikidata Toolkit [13]? How do you see reasoning engines using P31 and P279 in the future, if at all? Thanks, Eric https://www.wikidata.org/wiki/User:Emw [1] https://www.wikidata.org/wiki/WT:MB#Distinguishing_between_genes_and_proteins [2] https://www.wikidata.org/wiki/WT:MB#Human.2Fmouse.2F..._ID [3] https://www.wikidata.org/wiki/User:ProteinBoxBot. Chinmay Nalk ( https://www.wikidata.org/wiki/User:Chinmay26) did all the work on this, with input from WD:MB. [4] https://www.wikidata.org/wiki/Wikidata:WikiProject_Mineralogy [5] http://tools.wmflabs.org/wikidata-todo/tree.html?q=Q15281399rp=279lang=en [6] http://tools.wmflabs.org/wikidata-todo/tree.html?q=Q796194rp=279lang=en [7] http://apps.who.int/classifications/icd10/browse/2010/en [8] https://en.wikipedia.org/wiki/Template:Surgeries [9] https://www.wikidata.org/w/index.php?title=Wikidata:Database_reports/Popular_propertiesoldid=125595374 [10] Examples include - https://www.wikidata.org/wiki/Wikidata:Project_chat#chemical_element - https://www.wikidata.org/wiki/Wikidata:Project_chat/Archive/2013/12#Top_of_the_subclass_tree - https://www.wikidata.org/wiki/Wikidata:Project_chat/Archive/2014/01#Question_about_classes.2C_and_.27instance_of.27_vs_.27subclass.27 [11] http://tools.wmflabs.org/wikidata-todo/tree.html?q=Q164950rp=279lang=en [12] http://korrekt.org/page/The_Incredible_ELK [13] https://www.mediawiki.org/wiki/Wikidata_Toolkit On Mon, May 5, 2014 at 12:46 PM, Markus Kroetzsch markus.kroetz...@tu-dresden.de wrote: Hi, I got interested in subclass of (P279) and instance of (P31) statements recently. I was surprised by two things: (1) There are quite a lot of subclass of statements: tenth of thousands. (2) Many of them make a lot of sense, and (in particular) are not (obvious) copies of Wikipedia categories. My big question is: who is creating all these statements and how is this done? It seems too much data to be created manually, but I don't see obvious automated approaches either (and there are usually no references given). I also found some rare issues. A subclass of B should be read as Every A is also a B. For example, we have Every piano (Q5994) is also a keyboard instrument (Q52954). Overall, the great majority of cases I looked at had remarkably sane modelling (which reinforces my big question). But there are still cases where subclass of is mixed up with instance of. For example,
