Thursday, December 20, 2018

Enhanced exploitation of concordances in type corpora

Today, I extended some Nomisma APIs (for weights and the widget that populates images in Numishare-based type corpora browse pages) as well as SPARQL queries in Numishare itself to make better use of concordances between corpora that we are encoding in our data and exposing as skos:exactMatch URIs in our RDF outputs.

I had recently extended these queries to support the display of subtypes in browse pages and under the main "Type Examples" heading on coin type record pages (e.g., on The logic behind this was to provide a better UI for researchers to view example images without having to drill down one or more levels to see individual specimens, particularly within Seleucid Coins Online, which routinely goes two levels down from the parent type.

With the launch of Ptolemaic Coins Online, which contains a fairly comprehensive concordance with Price URIs defined in PELLA for the earlier Alexander types, I felt we were leaving a lot of functionality on the table by not exploiting these links. They are exposed as skos:exactMatch properties in the RDF that is published to the SPARQL endpoint. The queries were extended in several areas of the codebase into the following:

{ ?object a nmo:NumismaticObject ;
 nmo:hasTypeSeriesItem <typeURI>}
UNION { <typeURI> skos:exactMatch ?match .
?object nmo:hasTypeSeriesItem ?match ;
  a nmo:NumismaticObject }
UNION { ?broader skos:broader+ <typeURI> .
?object nmo:hasTypeSeriesItem ?broader ;
  a nmo:NumismaticObject }

Since many of our partners have already cataloged and contributed coins with Price numbers, but have either not cataloged with the Svoronos 1904 or Coins of the Ptolemaic Empire numbers or have simply not provided data dumps for PCO, this has substantially extended the coverage of PCO. There are several hundred coins in the ANS collection with Price numbers, but no Svoronos. Instead of launching PCO with around 1,200 specimens from 4 or 5 museums, we are instead launching with 1,700 from 10.

The impact is especially noticeable among the earliest Ptolemaic coinage, where there is significant overlap with PELLA (the first several pages of the PCO browse page).

PCO browse page 1

Furthermore, we are able to exploit links to IGCH hoards that have been cataloged in the ANS collection for coins only linked to Price numbers. CPE 19 and 20 are both linked to more than 100 specimens (primarily in the ANS collection), and are each linked linked to several coin hoards.

CPE 19

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