Issue 294: E55 Type relations

Starting Date: 
2015-12-28
Working Group: 
3
Status: 
Open
Background: 

Posted by Martin on 28/12/2015

Dear All,

I wish you all a Happy New Year!

Please see this document to discuss properties of E55 Type
for archaeological reasoning
 


 

Posted by Øyvind  on 6/1/2016

Dear all,

This was an interesting read. I have a question:

I do not understand the logic of the last paragraph in page 2. First they talk about

[1] “a specific time period in which and only in which objects of a given type have been created”

and then they go on to talk about

[2] no finds from other periods.

[2] is much weaker than [1] but is seems to me that [2] is still used as evidence for [1]. I do not argue that is wrong to use it as evidence (there are never proofs in heritage based research of this kind) but I fail to see how it can be seen as a closed world assumption — that is pretty strong.

I think it is a good choice to model it as an implicit restriction, though; the modelling looks fine. It is more the use of “closed world” I wonder about.


As for the choice between modelling of periods as timespans or periods I think this feeds well into the discussion we have on space-time modelling and this document will be useful for the discussions in Prato.


Posted by Wolfgang Schmidle on 6/1/2016

Co-author here. Yes, we use [2] as evidence for [1], and if new evidence is unearthed, the "restricted" statement may turn out to be false.

The "closed world assumption" was only meant as an analogy. We do not argue that a "Restriction" statement in the sense of a bounding box can be inferred from the given "appears in" and "typical for" statements. (Maybe one should also distinguish between the knowledge of the archaeologist and the — possibly incomplete — list of actual "appears in" and "typical for" statements.) Instead, it probably needs to be an explicit new statement, and the inferred statement in Figure 3 should probably have a different name that doesn't suggest anything but an inferred statement.

The point of the Restriction being a timespan rather than a period was, I think, that the sum of periods may not automatically be a period itself. In particular, it may not be identical to the "production of the Paukenfibel" period. However, in Figure 3 we assume that there is at least no temporal gap inbetween. And timespan means more or less the same as spacetime volume here since the area in the example is always the same.

By the way, we have a similar problem in our gazetteer, where we need to express the fact that a given region is part of the union of three other regions. 


Posted by Martin on 6/1/2016

Dear Wolfgang,

My opinion to your questions:

Is it more precise to model the sum of periods as a timespan or a period itsself?

It is more precise to model it as a period, in case this period has a common unity criterion.
It is equally more precise to model it as a spacetime volume, but RDF has no construct to describe that
an STV is exactly the sum of a set of components. The same holds for periods.

How should a hiatus be expressed then? So the stopped and later on picked up
usage of the same object. As a second timespan / period attached to the appearance of an object?

I think it needs a negative property. To be discussed with Carlo Meghini.

• Relation of Types and objects that refer to that type: Is it important to have at least
  one object for a “appears in” assignment to refer to.

Well, yes for capturing the argument. If the object is described, the "appears in" could be inferred.

I think a "restricted to" would be a good property. It is more than the sum of "appears in". It requires
an argument of having sufficiently dense observation at other times and sites, or historical sources. 


Posted by Øyvind  on 7/1/2016

Thank you, Wolfgang! This makes sense to me.

The criteria for what is a period have to be decided by the experts. Yet, I think it is pretty clear that the Renaissance Augustus is a different period from the one in antiquity. Connected, but different.

 

 

Old Proposal: 

Sent it by Chryssoula to George on 19/7/2016

George

There is an old issue about the relation between period and time. You may find attached all we have about these. Could you make a summary in order to introduce to the sig? 

 

Attachment 1: issue 243 Times and Periods

Attachment 2: Issue 294 E55 Type Relations

Attachment 3: Paper by Philipp Gerth, Wolfgang Schmidle

Current Proposal: 

Posted by George Bruseker on 2/8/2016


I have re read all these and am prepared to reintroduce the issue. 

*****************

Initiating Issue:

 

Martin

 

May be it's time to propose a link between a period and a type. Very characteristic reasoning in archaeology, biology and geology ("Leitfossil").
Has anybody examples of data structures supporting such data?

***********************************

Two Proposals:

Achille Proposal

(a) E55 Type.PXX objects of a type appear in: E4 Period.

Note: objects of a specific type are ascribed to a specific period: Example: " the

Etruscan fibulae appear in the Etruscan Period"

(b) E55 Type.PXX object of a type define: E4 Period

Note: objects of a specific style define an artistic period:

Example: "the geometric class of vases define the Geometric Period of Greek art"

Wolfgang Proposal

Type with relation

Typical for to Period

Leitfossil, is the object which has been determined to be characteristic to a period thanks to particular analysis, and is definitive for the period. Along with other indications its presence at a spot can help date a context.

(Question – so good documentation practice should always point to who this was determined by and using what technique)

Appears in for Period

Object continues to be used or found in a period, but is not unique and typical for it. The object is not produced in this period

Restricted to:

Defined as the sum of all appears in and typical for relations, proposed to be modelled as a time span (not to make an arbitrary period)

Martin replies:

Is it more precise to model the sum of periods as a timespan or a period itsself?

It is more precise to model it as a period, in case this period has a common unity criterion.

It is equally more precise to model it as a spacetime volume, but RDF has no construct to describe that an STV is exactly the sum of a set of components. The same holds for periods.

How should a hiatus be expressed then? So the stopped and later on picked up

usage of the same object. As a second timespan / period attached to the appearance of an object?

I think it needs a negative property. To be discussed with Carlo Meghini.

 

 

 

 

Reference to Issues:

Meetings discussed: