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 been encouraging!)
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
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., https://www.ted.com/speakers
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 identifiers.
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 external identifiers.
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 ID)?
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 the back-end.
(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
Von: Wikidata [mailto:email@example.com] Im
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
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 box.
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 human:
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 off-list).
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>
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
And many thanks to those who have already provided feedback! :)
José & Aidan
On 09-01-2018 14:18, Aidan Hogan wrote:
A Masters student of mine (José Moreno in CC) has been working on a
faceted navigation system for (large-scale) RDF datasets called "GraFa".
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:
Aidan and José
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