Understood, yes! The ability to select entities with any value for some
property is something I agree would be a useful next step, and the use-case
you mention of something like a Wikidata/GraFa exploration of external
resources is very interesting! Thanks!
There are some technical reasons why it would not be so trivial right
now, mostly in the back-end relating to caching. GraFa caches all facets
for all possible queries that generate more than 50,000 results. This is
how we can generate the exact facets, for example, for the 352,063 people
from the U.S. in under a second (the data are precomputed; if I recall
correctly, otherwise the query would take around 30 seconds). The ability
to query for existential values (a property with any value) will increase a
lot the number of queries we would have to cache. I think it would still be
feasible in the current system, but we would have to do some work. In any
case, I have added it to the issue tracker!
(On a more organisational side, I'm just noticing now that there's quite
a few open issues on the tracker to look at, but José Moreno, the masters
student who did all the hard work on GraFa, is currently finalising his
thesis and preparing to defend. Hence development on Grafa is paused for
the moment but I hope we can find a way to continue since the feedback has
On 07-03-2018 9:04, Neubert, Joachim wrote:
Thanks for your reply! My suggestion indeed was to feed in a property
(e.g. " P2611") - not a certain value or range of values for that property
- and to restrict the initial set to all items where that property is set
(e.g., all known TED speakers in Wikidata).
That would allow to apply further faceting (e.g., according to
occupation or country) to that particular subset of items. In effect it
would offer an alternate view to the original database (e.g.,
which is organized by topic and by event).
Thus, the full and often very rich structured data of Wikidata could be
used to explore external datasets which are linked to WD via external
Being able to browse their own special collections by facets from
Wikidata could perhaps even offer an incentive to GLAM institutions to
contribute to Wikidata. It may turn out much easier to add some missing
data to Wikidata, in relation to introducing a new field in their own
database/search interface, and populating it from scratch.
So I'd suggest that additional work invested into GraFa here could pay
out in a new pattern of use for both Wikidata and collections linked by
Von: Wikidata [mailto:firstname.lastname@example.org] Im Auftrag
von Aidan Hogan
Gesendet: Mittwoch, 7. März 2018 06:16
Betreff: Re: [Wikidata] GraFa: Faceted browser for RDF/Wikidata [thanks!]
On 14-02-2018 7:32, Neubert, Joachim wrote:
Hi Aidan, hi José,
I'm a bit late - sorry!
What came to my mind as an perhaps easy extension: Can or could the
browser be seeded with an external property (for
example P2611, TED speaker
That would allow to browse some external dataset (e.g., all known TED
speakers) by the facets provided by Wikidata.
Thanks for the suggestion! While it might seem an easy extension,
unfortunately that would actually require some significant changes since
GraFa only considers values that have a label/alias we can auto-complete on
(which in the case of Wikidata means, for the most part, Q* values).
While it would be great to support datatype/external properties, we
figured that adding them to the system in a general and clean way would not
be trivial! We assessed that some such properties require ranges (e.g.,
date-of-birth or height), some require autocomplete (e.g., first name),
etc. ... and in the case of IDs, it's not clear that these are really
useful for faceted browsing perhaps since they will jump to a specific
value. Hence it gets messy to handle in the interface and even messier in
(A separate issue is that of existential values ... finding entities
that have some value for a property as your example requires. That would
require some work, but would be more feasible!)
> Von: Wikidata
> Auftrag von Aidan Hogan
> Gesendet: Donnerstag, 8. Februar 2018 21:33
> An: Discussion list for the Wikidata project.
> Cc: José Ignacio .
> Betreff: Re: [Wikidata] GraFa: Faceted browser for RDF/Wikidata
> Hi all,
> On behalf of José and myself, we would really like to thank the
> people who tried out our system and gave us feedback!
> Some aspects are left to work on (for example, we have not tested for
> mobiles, etc.). However, we have made some minor initial changes
> reflecting some of the comments we received (adding example text for
> the type box, clarifying that the numbers refer to number of results
> not Q codes, etc.):
> To summarise some aspects of the work and what we've learnt:
> * In terms of usability, the principal lesson we have learnt (amongst
> many) is that it is not clear for users what is a type. For example,
> when searching for "popes born in Poland", the immediate response of
> users is to type "pope" rather than "human" or "person"
in the type
> In a future version of the system, we might thus put less emphasis on
> starting the search with type (the original reasoning behind this was
> to quickly reduce the number of facets/properties that would be shown).
> Hence the main conclusion here is to try to avoid interfaces that
> centre around "types".
> * A major design goal is that the user is only ever shown options
> that lead to at least one result. All facets computed are exact with
> exact numbers. The technical challenge here is displaying these
> facets with exact numbers and values for large result sizes, such as
> This is achieved through caching. We compute all possible queries in
> the data that would yield >50,000 results (e.g., human->gender:male,
> human->gender:male->country:United States, etc.). We then compute
> facets offline and cache them. In total there's only a couple of
> hundred such queries generating that many results. The facets for
> other queries with fewer than 50,000 results are computed live. Note
> that we cannot cache for keyword queries (instead we just compute
> facets for the first
> 50,000 most relevant results). Also, if we add other features such as
> range queries or sub-type reasoning, the issue of caching would
> become far more complex to handle.
> In any case, thanks again to all those who provided feedback! Of
> course further comments or questions are welcome (either on- or
> Likewise we will be writing up a paper describing technical aspects
> of the system soon with some evaluation results. Once it's ready we
> will of course share a link with you.
> Aidan and José
> -------- Forwarded Message --------
> Subject: Re: GraFa: Faceted browser for RDF/Wikidata [feedback
> Date: Mon, 15 Jan 2018 11:47:18 -0300
> From: Aidan Hogan <aidhog(a)gmail.com>
> To: Discussion list for the Wikidata project.
> CC: José Ignacio . <joshep(a)live.cl>
> Hi all!
> Just a friendly reminder that tomorrow we will close the
> questionnaire so if you have a few minutes to help us out (or are
> just curious to see our faceted search system) please see the links
> and instructions below.
> And many thanks to those who have already provided feedback! :)
> José & Aidan
> On 09-01-2018 14:18, Aidan Hogan wrote:
>> Hey all,
>> A Masters student of mine (José Moreno in CC) has been working on a
>> faceted navigation system for (large-scale) RDF datasets called
>> The system is available here loaded with a recent version of Wikidata:
>> Hopefully it is more or less self-explanatory for the moment. :)
>> If you have a moment to spare, we would hugely appreciate it if you
>> could interact with the system for a few minutes and then answer a
>> quick questionnaire that should only take a couple more minutes:
>> Just for the moment while the questionnaire is open, we would kindly
>> request to send feedback to us personally (off-list) to not affect
>> others' responses. We will leave the questionnaire open for a week
>> until January 16th, 17:00 GMT. After that time of course we would be
>> happy to discuss anything you might be interested in on the list. :)
>> After completing the questionnaire, please also feel free to visit
>> or list something you noticed on the Issue Tracker:
>> Many thanks,
>> Aidan and José
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