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Thesauri of Historical PeriodsA Proposal for Standardization

Martin Doerr, Athina Kritsotaki

Heraklion, Crete, June 18 2015

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What does “Period” mean?Period definition by CIDOC CRM (ISO/CD21127):Period definition by CIDOC CRM (ISO/CD21127):

“ “This class comprises sets of coherent phenomena or cultural This class comprises sets of coherent phenomena or cultural manifestations bounded in time and space. It is the social or physical manifestations bounded in time and space. It is the social or physical coherence of these phenomena that identify an E4 Period and not the coherence of these phenomena that identify an E4 Period and not the associated spatio-temporal bounds. These bounds are a mere associated spatio-temporal bounds. These bounds are a mere approximation of the actual process of growth, spread and retreat. approximation of the actual process of growth, spread and retreat. Consequently, different periods can overlap and coexist in time and Consequently, different periods can overlap and coexist in time and space, such as when a nomadic culture exists in the same area as a space, such as when a nomadic culture exists in the same area as a

sedentary culture. …”sedentary culture. …”

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Problem Confusion Confusion of time with of time with phenomenonphenomenon in spacetimein spacetime ConfusionConfusion of definition and spatiotemporal approximation of definition and spatiotemporal approximation VaguenessVagueness of traditional definition of traditional definition ConfusionConfusion of evidence and conclusion, definition and of evidence and conclusion, definition and

interpretationinterpretation ConfusionConfusion of general characteristics and distinct of general characteristics and distinct

characteristicscharacteristics Lack of communicationLack of communication – different scientists use different – different scientists use different

definitions and different terminologydefinitions and different terminology

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General models for thesauri (ISO2788) fail to General models for thesauri (ISO2788) fail to capture period definition.capture period definition.

No satisfactory solution proposed so far. We have No satisfactory solution proposed so far. We have presented this approach CAA 2004/ CIDOC 2006presented this approach CAA 2004/ CIDOC 2006

Related projects: Related projects: PeriodO, AAT (Getty), Perseus, PeriodO, AAT (Getty), Perseus, MIDAS, CLIO, CIDOC CRM.MIDAS, CLIO, CIDOC CRM.

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Objectives

Provide the specification of a comprehensive document Provide the specification of a comprehensive document structure for thesauri of periods based on archaeological structure for thesauri of periods based on archaeological theory, computer science and the CIDOC CRM. theory, computer science and the CIDOC CRM.

Provide a standard format for defining periods.Provide a standard format for defining periods.

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This will enable us to:This will enable us to:

- Standardize forms and templates- Standardize forms and templates

- Organize archaeological information in a computerized - Organize archaeological information in a computerized environment environment

- Classify museum objects more consistently by period of - Classify museum objects more consistently by period of creation creation

- Identify better contemporary finds in archaeological - Identify better contemporary finds in archaeological research and excavations research and excavations

- Make easier the communication and knowledge sharing - Make easier the communication and knowledge sharing between scientists between scientists

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The presented method and thesaurusThe presented method and thesaurus

does not aimdoes not aim to analyze periods or to prescribe a to analyze periods or to prescribe a correct scientific opinion about chronological correct scientific opinion about chronological problems!problems!

Instead, it aimsInstead, it aims to provide : to provide : an overview of scientific opinions an overview of scientific opinions the relationships between multiple period the relationships between multiple period

definitions definitions

via a methodical approach…via a methodical approach…

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Approach A schema specification (for the creation and management of A schema specification (for the creation and management of

period thesauri) in the form of an XML period thesauri) in the form of an XML DTDDTD for:for: data data acquisition andacquisition and exchangeexchange supporting a process of submission - redefinitionsupporting a process of submission - redefinition replacing missing linking possibilityreplacing missing linking possibility

A derived schema specification A derived schema specification for:for: data data storagestorage supporting linking (and possibly versioning)supporting linking (and possibly versioning)

an examplean example (of period names within the Helladic period) as (of period names within the Helladic period) as a proof of concepta proof of concept

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Approach the schema describes the schema describes a single period concept as a single period concept as

a single document a single document thatthat may linkmay link to other period definitions, to other period definitions, places,places, literature citationsliterature citations

A period thesaurus = a set of A period thesaurus = a set of linkedlinked period period definitionsdefinitions

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Approach

An exampleAn example of period names within the Helladic period as of period names within the Helladic period as as proof of conceptas proof of concept

: implemented in XML, : implemented in XML,

demonstrating problems of identification and demonstrating problems of identification and classification.classification.

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Period DTD Major Elements1.1. metadata about the metadata about the conceptionconception of the period of the period

2.2. multilingual multilingual terminology terminology naming the periodnaming the period

3.3. definitiondefinition (defining criteria & events) (defining criteria & events)

4.4. spatiotemporal spatiotemporal extentextent, analysis and spatiotemporal , analysis and spatiotemporal relationshipsrelationships

5.5. further description : further description : characteristiccharacteristic attributes and cultural attributes and cultural influencesinfluences

6.6. literature citationliterature citation

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Definition of period Period Period is definedis defined by distinct (“defining”) by distinct (“defining”)

criteria based on the archaeological contextscriteria based on the archaeological contexts

rather than rather than by time and place.by time and place.

““Defining criteriaDefining criteria” are: types of phenomena or interrelated ” are: types of phenomena or interrelated phenomena that determine the unity and identify the phenomena that determine the unity and identify the cultural continuity of a period.cultural continuity of a period.

- - Their occurrence determines the spatiotemporal extentTheir occurrence determines the spatiotemporal extent

““Defining criteriaDefining criteria” are distinguished from the “” are distinguished from the “general general characteristicscharacteristics” that simply describe periods and other ” that simply describe periods and other distinct characteristics (“Index fossil”) that do distinct characteristics (“Index fossil”) that do not not determinedetermine the spatiotemporal extent the spatiotemporal extent

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Period definition: DTD

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Period definition and events

Events Events are related to period definition.They may are related to period definition.They may markmark limits limits of the temporal extent of a period.of the temporal extent of a period.

Events Events may may happenhappen at the beginning or at the end of a period, at the beginning or at the end of a period, but they but they do notdo not causecause a period. They are seen as a period. They are seen as occasionoccasion rather than cause.rather than cause.

Those events Those events do not definedo not define the periods the periods themselves as cultural themselves as cultural phenomena.phenomena.

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Spatiotemporal extentSpatiotemporal extent TheThe extent of a periodextent of a period (in time and space) is (in time and space) is

approximated by a description of spatial and approximated by a description of spatial and

temporal outer bounds (“box”). temporal outer bounds (“box”).

The extent of a period may be refined as a temporal The extent of a period may be refined as a temporal

evolution (analysis) over spaceevolution (analysis) over space..

The spatiotemporal extent may also constraint by The spatiotemporal extent may also constraint by

spatialspatial

temporaltemporal, and, and

spatiotemporal relations to other periodsspatiotemporal relations to other periods

resulting from archaeological evidence (not absolute dating)resulting from archaeological evidence (not absolute dating)

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Spatiotemporal extent: DTD

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t

x

y

Space time analysis

“Box” of outer bounds

Inner “Box” 1

Inner “Box” 2

“True” extent

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Characteristics attributes: DTDCharacteristics attributes: DTD

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An example of period thesaurus

An example thesaurus of period names of An example thesaurus of period names of Helladic Helladic prehistoryprehistory has been developed. has been developed.

Different types of periods have been selected in order to Different types of periods have been selected in order to prove the complexity of period relationships and prove the complexity of period relationships and definition. They reflectdefinition. They reflect different different scientificscientific opinions/ opinions/ interpretations interpretations – definitions– definitions..

The example is used to confirm the structure of the The example is used to confirm the structure of the schema.schema.

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Example of different “defining criteria”

PeriodPeriod ( (social-politicalsocial-political):):

““Old Palace”Old Palace”

Definition based on:Definition based on:

Social-political systemSocial-political system

Description:Description:Foundation of palaces Foundation of palaces – palatial society (first – palatial society (first destruction of palaces at the end destruction of palaces at the end of period)of period)

Interpretation by:Interpretation by: N.Platon 1958 N.Platon 1958

Time-span (approximately)Time-span (approximately): : 2000/1900 2000/1900 B.CB.C- 1700- 1700 B.CB.C

Period (Period (stylisticstylistic):):““MMIB”MMIB”Definition based on:Definition based on:Pottery StylePottery StyleDescription:Description: Development of Development of

MMIb Style (Barbotine, MMIb Style (Barbotine, Dark on Light, growing Dark on Light, growing polychromy on potterry)polychromy on potterry)

Interpretation by:Interpretation by: A.Evans A.Evans 19211921

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Example of periods and events

Event (“terminating” or “starting”): Event (“terminating” or “starting”): The eruption The eruption of the volcano in Thera : of the volcano in Thera :

Date: 1646 or 1628 B.CDate: 1646 or 1628 B.C

was used as a was used as a chronological chronological end markend mark of of Late Cycladic I period, now as Late Cycladic I period, now as starting starting markmark..LCI period is defined by a combination of LCI period is defined by a combination of cultural phenomena and not by the cultural phenomena and not by the dramatic event of the eruption.dramatic event of the eruption.

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Conclusions A formal methodologyA formal methodology has been developed to capture has been developed to capture

period definition and description – it provides period definition and description – it provides the first the first specification of document structure for thesauri of periodsspecification of document structure for thesauri of periods, , which goes beyond general models for thesauri. It is based which goes beyond general models for thesauri. It is based on CIDOC specifications, archaeological reasoning and on CIDOC specifications, archaeological reasoning and computer science.computer science.

A schema is proposed as a guide to good practice A schema is proposed as a guide to good practice (possible (possible standard)standard) for creating thesauri of periods. for creating thesauri of periods.