Select Under Counts in Presance of Reasoning

Support Bug
1

Hi,

As many of you know, I have a data set which is the genealogies of particular people form early Ireland. I was doing some searching for the ancestors of a particular person so I ran the query below against my data with Stardog 7.1.0 and I was specifically looking at this file with Reasoning turned on (and sameAs Full, punning on):

prefix rel: <http://purl.org/vocab/relationship/>
prefix foaf:  <http://xmlns.com/foaf/0.1/>

select ?a
from <tag:stardog:api:context:all> 
where {
    ?a rel:ancestorOf <http://example.com/LU/de_genelogia_con_culaind.trig#CúCulaind>
}

This query returned 25 results:

a
http://example.com/LU/de_genelogia_con_culaind.trig#Soaldaim-4d4d44a4
http://example.com/LU/de_genelogia_con_culaind.trig#Dubtaigi
http://example.com/LU/de_genelogia_con_culaind.trig#Cubair-76516a19
http://example.com/LU/de_genelogia_con_culaind.trig#Lir-46304844
http://example.com/LU/de_genelogia_con_culaind.trig#Cusantin
http://example.com/LU/de_genelogia_con_culaind.trig#Adachair
http://example.com/LU/de_genelogia_con_culaind.trig#Báetain
http://example.com/LU/de_genelogia_con_culaind.trig#Midgni
http://example.com/LU/de_genelogia_con_culaind.trig#Úachaill
http://example.com/LU/de_genelogia_con_culaind.trig#CaisClothaig
http://example.com/LU/de_genelogia_con_culaind.trig#Cermata-1bbbbd55
http://example.com/LU/de_genelogia_con_culaind.trig#inDagdai-dd481355
http://example.com/LU/de_genelogia_con_culaind.trig#Inde
http://example.com/LU/de_genelogia_con_culaind.trig#Dorain
http://example.com/LU/de_genelogia_con_culaind.trig#Nomail
http://example.com/LU/de_genelogia_con_culaind.trig#Condlai
http://example.com/LU/de_genelogia_con_culaind.trig#Memnón
http://example.com/LU/de_genelogia_con_culaind.trig#Samrith
http://example.com/LL/dáil_araide.trig#puithe
http://example.com/LU/de_genelogia_con_culaind.trig#Buithe
http://example.com/LU/de_genelogia_con_culaind.trig#Tigerndmais
http://example.com/LU/de_genelogia_con_culaind.trig#Follaig
http://example.com/LU/de_genelogia_con_culaind.trig#Ethrióil
http://example.com/Laud_Misc_610/CGH/senchus_síl_hérimóin_annso_fo_héirind.trig#IarélFaíth
http://example.com/Laud_Misc_610/CGH/senchus_síl_hérimóin_annso_fo_héirind.trig#Hérimón

If you look in the file, you will notice that #Lir-46304844 is the same as #Lir and as such the results should contain #Nelruaid. This is one specific example but there are plenty more missing. As an aside, I also ran the following query:

prefix rel: <http://purl.org/vocab/relationship/>

select ?o
from <tag:stardog:api:context:all> 
where {
    <http://example.com/LU/de_genelogia_con_culaind.trig#Lir> rel:childOf ?o
}

This returns the expected outcome 2: http://example.com/LU/de_genelogia_con_culaind.trig#Nelruaid and http://example.com/LU/de_genelogia_con_culaind.trig#Cusantin.

This could be because I do not understand RDF Datasets well enough to know how that effects reasoning but even without that, there are missing individuals who should be in the result set.

I am happy, as always, to share a dump of the database if needed.

Thank you for your time.

2

So, I had a chance to try this against an alternative to Stardog and it reports back 332 results, which is much closer to what I was expecting and it includes the URLs which I was expecting from Stardog. This means that I believe there is a very real bug in the way in which Stardog deals with this situation. I hope someone can look at this soon because I would think this is effecting other users as well as myself.

3

I haven't had a chance to look at this yet. I need to find some time to sit down, download your dataset and understand it a bit but I can point you in the direction that I would start looking first. My first guess would be that it's only returning a single url for each individual. SameAs reasoning will pick a random url out of the several possible urls for an individual and use that as the canonical url for that thing. So if you had a dateset with :satchmo and :Louis_armstrong you're result will only contain one or the other depending on which one was picked but not both.

4

Thanks! Yeah, it can be time consuming to sit down and sort through these things. Yes, I know that owl:sameAs relations are materialized and one is chosen as the "canonical" URL. That is not the problem: the problem is expected URLs like http://example.com/LU/de_genelogia_con_culaind.trig#Elathan and http://example.com/LU/de_genelogia_con_culaind.trig#Nelruaid are not in the result set. These are not in any owl:sameAs triple as these URLs are unique to the particular genealogy so I do not believe it is a misunderstanding of owl:sameAs materialization.

5

Thanks. That gives me somewhere to start digging. I'll let you know if I find anything but like you mentioned maybe it's just a bug.

6

Hi Everyone,

I have been away from this project for a bit due to life events but I came back to try the newest Stardog (7.2) to see if this was still a problem but sadly, it is. I am still getting this as a problem. There output of the query from the original post using 7.2 is the same (using sameAs FULL and Punning).

As an aside, I used Ontotext's GraphDB on the same query and I am getting expected results which is why I believe this is a bug with Stardog and not a bug with my query or my understanding.

I would be happy to provide a dump of the database and answer any questions that you may have.