Posts Tagged ‘RDF’

OEDUc: Disambiguating EDH person RDF working group

Tuesday, July 25th, 2017

One of the working groups at the Open Epigraphic Data Unconference (OEDUc) meeting in London (May 15, 2017) focussed on disambiguating EDH person RDF. Since the Epigraphic Database Heidelberg (EDH) has made all of its data available to download in various formats in an Open Data Repository, it is possible to extract the person data from the EDH Linked Data RDF.

A first step in enriching this prosopographic data might be to link the EDH person names with PIR and Trismegistos (TM) references. At this moment the EDH person RDF only contains links to attestations of persons, rather than unique individuals (although it attaches only one REF entry to persons who have multiple occurrences in the same text), so we cannot use the EDH person URI to disambiguate persons from different texts.

Given that EDH already contains links to PIR in its bibliography, we could start with extracting (this should be possible using a simple Python script) and linking these to the EDH person REF. In the case where there is only one person attested in a text, the PIR reference can be linked directly to the RDF of that EDH person attestation. If, however (and probably in most cases), there are multiple person references in a text, we should try another procedure (possibly by looking at the first letter of the EDH name and matching it to the alphabetical PIR volume).

A second way of enriching the EDH person RDF could be done by using the Trismegistos People portal. At the moment this database of persons and attestations of persons in texts consists mostly of names from papyri (from Ptolemaic Egypt), but TM is in the process of adding all names from inscriptions (using an automated NER script on the textual data from EDCS via the EAGLE project). Once this is completed, it will be possible to use the stable TM PER ID (for persons) and TM person REF ID (for attestations of persons) identifiers (and URIs) to link up with EDH.

The recommended procedure to follow would be similar to the one of PIR. Whenever there’s a one-to-one relationship with a single EDH person reference the TM person REF ID could be directly linked to it. In case of multiple attestations of different names in an inscription, we could modify the TM REF dataset by first removing all double attestations, and secondly matching the remaining ones to the EDH RDF by making use of the order of appearance (in EDH the person that occurs first in an inscription receives a URI (?) that consists of the EDH text ID and an integer representing the place of the name in the text (e.g., http://edh-www.adw.uni-heidelberg.de/edh/person/HD000001/1 is the first appearing person name in text HD000001). Finally, we could check for mistakes by matching the first character(s) of the EDH name with the first character(s) of the TM REF name. Ultimately, by using the links from the TM REF IDs with the TM PER IDs we could send back to EDH which REF names are to be considered the same person and thus further disambiguating their person RDF data.

This process would be a good step in enhancing the SNAP:DRGN-compliant RDF produced by EDH, which was also addressed in another working group: recommendations for EDH person-records in SNAP RDF.

OEDUc: recommendations for EDH person-records in SNAP RDF

Monday, July 3rd, 2017

At the first meeting of the Open Epigraphic Data Unconference (OEDUc) in London in May 2017, one of the working groups that met in the afternoon (and claim to have completed our brief, so do not propose to meet again) examined the person-data offered for download on the EDH open data repository, and made some recommendations for making this data more compatible with the SNAP:DRGN guidelines.

Currently, the RDF of a person-record in the EDH data (in TTL format) looks like:

<http://edh-www.adw.uni-heidelberg.de/edh/person/HD000001/1>
    a lawd:Person ;
    lawd:PersonalName "Nonia Optata"@lat ;
    gndo:gender <http://d-nb.info/standards/vocab/gnd/gender#female> ;
    nmo:hasStartDate "0071" ;
    nmo:hasEndDate "0130" ;
    snap:associatedPlace <http://edh-www.adw.uni-heidelberg.de/edh/geographie/11843> ,
        <http://pleiades.stoa.org/places/432808#this> ;
    lawd:hasAttestation <http://edh-www.adw.uni-heidelberg.de/edh/inschrift/HD000001> .

We identified a few problems with this data structure, and made recommendations as follows.

  1. We propose that EDH split the current person references in edh_people.ttl into: (a) one lawd:Person, which has the properties for name, gender, status, membership, and hasAttestation, and (b) one lawd:PersonAttestation, which has properties dct:Source (which points to the URI for the inscription itself) and lawd:Citation. Date and location etc. can then be derived from the inscription (which is where they belong).
  2. A few observations:
    1. Lawd:PersonalName is a class, not a property. The recommended property for a personal name as a string is foaf:name
    2. the language tag for Latin should be @la (not lat)
    3. there are currently thousands of empty strings tagged as Greek
    4. Nomisma date properties cannot be used on person, because the definition is inappropriate (and unclear)
    5. As documented, Nomisma date properties refer only to numismatic dates, not epigraphic (I would request a modification to their documentation for this)
    6. the D-N.B ontology for gender is inadequate (which is partly why SNAP has avoided tagging gender so far); a better ontology may be found, but I would suggest plain text values for now
    7. to the person record, above, we could then add dct:identifier with the PIR number (and compare discussion of plans for disambiguation of PIR persons in another working group)