Wednesday, May 15, 2019

Extending distribution and metrical analyses across corporate entities

I recently pushed some significant changes to the distribution and metrical analysis visualization features both in the Numishare platform and itself to differentiate personal from corporate authories when querying typological data.

Previously, the authority could be selected as a query parameter for generating a visualization, but the underlying SPARQL query merely extracted the values associated explicitly with the nmo:hasAuthority property for coin types. This means it was impossible to compare one kingdom to another since the relationship between a type and an overarching corporate entity is nearly always made between the ruler designated as the nmo:hasAuthority and the ruler's Nomisma RDF that links the ruler concept to the corporate entity using the W3C organization ontology. For example, Ptolemy I is linked to the Ptolemaic Empire with the following model:

nm:ptolemy_i org:hasMembership ?membership .
?membership a org:Membership ;
    org:organization nm:seleucid_empire;
    org:role nm:authority.

Using this model, we are able to use the Nomisma SPARQL endpoint to extract the distinct corporate entities that minted tetradrachms with the following query:

SELECT DISTINCT ?kingdom ?label WHERE {
  ?coinType a nmo:TypeSeriesItem;
              nmo:hasDenomination nm:tetradrachm .
  {?coinType nmo:hasAuthority ?kingdom}
  UNION {?coinType nmo:hasAuthority ?auth .
        ?auth org:hasMembership/org:organization ?kingdom }
  ?kingdom a foaf:Organization ;
             skos:prefLabel ?label FILTER (langMatches(lang(?label), "en"))

Bear in mind that we have to use a UNION query to join coin types that may have the corporate authority explicitly expressed in the nmo:hasAuthority. This is the case for later Seleucid coinage issued under the authority of the Roman Republic.

Now that we are able to exploit the relationships between people and corporate entities in the Nomisma data, we can begin to construct new queries and visualizations across broader periods of time, for example to compare the average weights of tetradrachms issued broadly by the Seleucid vs. Ptolemaic Empires over nearly three centuries. Or to compare the distribution of deities that appear on Seleucid vs. Ptolemaic coinage (for example,

Distribution of deities as appearing on Seleucid and Ptolemaic coinage

Here we can see the Ptolemaic affinity toward Athena compared to the prevalence of Apollo on Seleucid coinage, at least according to the the incomplete typological data we have published from the Ptolemaic Empire (Ptolemaic Coins Online only coins the gold and silver coinage through Ptolemy IV so far). This is one of a number of recent improvements to the query mechanisms in Numishare and Nomisma, and more should be expected in the coming months, especially to include the querying of legends and monograms.

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