Slides for paper delivered at the 2014 Computer Applications and Quantitative Methods in Archaeology Conference in Paris, France, on April 24, 2014. The authors are Adam Rabinowitz, Ryan Shaw, and Eric Kansa. The paper concerns Linked Data approaches to periodization of archaeological and historical information (abstract available at http://caa2014.sciencesconf.org/28428).

1. @perio_do
A Linked Data gazetteer to bridge
the gap between concept and usage
in archaeological periodization
Adam Rabinowitz, The University of Texas at Austin
Ryan Shaw, The University of North Carolina at Chapel Hill
Eric Kansa, Open Context and The University of California at Berkeley

2. The Iron Age: a very old period
And then in turn wide-browed Zeus established another, fifth
race of men, who were born on the much-nourishing earth. I
ought never to have been among this fifth race of men, but I
should have died before or been born later. For now it is a
race of iron: they never stop from toil and lament by day, nor
by night from wasting away.
Hesiod, Works and Days, 169c-178 (7th c. BC?)
Rabinowitz, Shaw, Kansa @perio_do CAA 2014 24.4.14

3. Getty AAT scope note for Iron Age
Refers to the period and culture associated with the third
age in the Three Age system developed by Christian
Jürgensen Thomsen in 1836. Iron Age culture typically
developed from the Bronze Age at the point when the
qualities of iron were exploited, particularly through
carburization, in the manufacture of tools, weapons, and
implements. It developed at different times in various parts
of the world, first appearing in the Middle East and
southeastern Europe around 1,200 BCE, and in China
around 600 BCE. In the Americas, it did not develop from
the Bronze Age but was introduced to Stone Age cultures by
European explorers.
Rabinowitz, Shaw, Kansa @perio_do CAA 2014 24.4.14

4. British Museum period thesaurus (XML)
Rabinowitz, Shaw, Kansa @perio_do CAA 2014 24.4.14

5. British Museum period thesaurus (RDF)
Rabinowitz, Shaw, Kansa @perio_do CAA 2014 24.4.14

6. British Museum period thesaurus (RDF)
skos:scopeNote:
The Early Cycladic period (3200BC – 2000BC) refers to
material produced in the Cyclades during the Aegean Early
Bronze Age. Although it is part of the tripartite scheme (Early,
Middle and Late) into which the Aegean Bronze Age is
conventionally divided, it is difficult to apply the same
subdivisions (I,II,III) as for Early Minoan or Early Helladic. For
this reason it is divided into partly overlapping cultural groups,
initially defined by Colin Renfrew. The three main groups used
to subdivide the period are Grotta-Pelos (q.v.), Keros-Syros
(q.v.) and Phylakopi I (q.v.).
Rabinowitz, Shaw, Kansa CAA 2014 24.4.14

7. ARENA Portal Period Search (ADS)
http://ads.ahds.ac.uk/arena/search/period.cfm
Rabinowitz, Shaw, Kansa @perio_do CAA 2014 24.4.14

8. FASTI Online Geographic Periodization
http://fastionline.org/
Rabinowitz, Shaw, Kansa @perio_do CAA 2014 24.4.14

9. STAR.timeline service client, English Heritage data
http://reswin1.isd.glam.ac.uk/STAR/UI/timelineclient.html
Rabinowitz, Shaw, Kansa @perio_do CAA 2014 24.4.14

10. DINAA and decentralized period concepts
Digital Index of North
American
Archaeology (DINAA)
• NSF funded publication of state
site file data (from regulatory
compliance)
• ~700 period concepts from 11
US-states
• PIs: David G. Anderson, Joshua
Wells
Rabinowitz, Shaw, Kansa @perio_do CAA 2014 24.4.14

11. Open Context “Time Tiles” (Kansa et al., SAA 2014)
• Need to define earliest and latest possible dates for a tiling grid
• Latest is 0 BP, example below is 1 Million BP (Open Context allows
10MYA).
• Recursive function to compute tile from earliest and latest BP date as
input. (Source code: https://github.com/ekansa/open-context-code)
• Tiles can be converted back to earliest and latest dates.
• Like map-tiles, time-tiles easily aggregate at different scales by
lumping together characters of the same value from left to right.
Shaded regions show different aggregations of time-tiles.
• Tiles allow arbitrary time ranges to be used in faceted search.
• Time-tiles can be combined with controlled vocabulary of named
periods (in development with DINAA).
1M-00000000122000110221
(Roman: 2000 – 1470 BP)
1M-00000000312010332212
(Iron Age: 3100 – 2500 BP)
1M-01001322312033201102
(Middle Paleolithic: 300KYA – 30KYA)
Rabinowitz, Shaw, Kansa @perio_do CAA 2014 24.4.14

12. Topotime, temporal geometry, and visualization
http://dh.stanford.edu/topotime/
Rabinowitz, Shaw, Kansa @perio_do CAA 2014 24.4.14

13. Topotime, temporal geometry, and visualization
http://dh.stanford.edu/topotime/
Rabinowitz, Shaw, Kansa @perio_do CAA 2014 24.4.14

14. Pleiades, Pelagios, and spacetime complexity
Rabinowitz, Shaw, Kansa @perio_do CAA 2014 24.4.14

15. The basic PeriodO data model
Rabinowitz, Shaw, Kansa @perio_do CAA 2014 24.4.14

16. An assertion expressed in JSON-LD
DOI for assertion (minted by
CDL EZID system)
Start and end dates expressed as
Julian Day Number
URI for authority (e.g. VIAF)
URI for geographic coverage
(e.g. GeoNames or Wikidata)
Rabinowitz, Shaw, Kansa @perio_do CAA 2014 24.4.14

17. Julian Day Numbers
• Interval endpoints (start, [latest start], end, [earliest end]) will be
normalized as Julian Day Numbers: float values expressed in
scientific notation.
• The number of significant digits expresses the precision:
Normalized
value
Significant
digits
Range interpretation
1.3E6 2
JDN 1,250,000
to JDN 1,350,000
1150BC ±150 years
1.30E6 3
JDN 1,295,000
to JDN 1,305,000
1150BC ±15 years
1.300E6 4
JDN 1,299,500
to JDN 1,300,500
1150BC ±1.5 years
Rabinowitz, Shaw, Kansa @perio_do CAA 2014 24.4.14

18. PeriodO Architecture
JSON-LD
JSON-LD
JSON-LD
JSON-LD
documents
git client
(power users &
core collaborators)
serves HTML5 app
proxy for EZID API
HTML5 app
(search, visualization, editing)
mints DOIs for
period assertions
Rabinowitz, Shaw, Kansa @perio_do CAA 2014 24.4.14

19. HTML5 Application
• Search and browse period assertions
comparable to Virtual International Authority File of
name authority clusters
• Visually compare temporal ranges of assertions
comparable to ARENA Portal period search chart or
the STAR.Timeline client
• Add and edit period assertions
edit data stored locally in browser, then push to
GitHub and issue a pull request
Rabinowitz, Shaw, Kansa @perio_do CAA 2014 24.4.14

20. Search and visualization use-cases
• What period terms are used to describe the
archaeological record in a particular place?
• What period terms are used to describe the
archaeological record during a particular time
range?
• What period terms are used to describe material
from a particular place AND time?
• What are the points of disagreement between
scholars with regard to particular period concepts?
• What chronological range do scholars agree on with
regard to particular period concepts?
Rabinowitz, Shaw, Kansa @perio_do CAA 2014 24.4.14

21. Assertions, Instances, and URIs
• If a range of assertions made at different points in time
are collected, can highlight scholarly disagreements and
diachronic changes in period concepts
• If period assertions can be connected with instances of
use (in publications or in datasets), chronological and
geographic scope can be refined and networks of
intellectual influence established
• With enough data, gazetteer could serve as machine-learning
training dataset for mining chronological
information from texts
• Period assertion URIs, like URIs for places and people,
can be used across datasets, allowing linking and
chronological reconciliation without enforcing use of a
single master period thesaurus
Rabinowitz, Shaw, Kansa @perio_do CAA 2014 24.4.14

22. Back to the Iron Age
Rabinowitz, Shaw, Kansa @perio_do CAA 2014 24.4.14

23. http://perio.do
We gratefully acknowledge the support of the National Endowment for the
Humanities and the NEH Office of Digital Humanities, the members of our
advisory board, and the partners whose period thesauri form our core dataset
Rabinowitz, Shaw, Kansa @perio_do CAA 2014 24.4.14