[Crm-sig] (Geographic) Place vs. SpaceTimeVolume (?)

Franco Niccolucci franco.niccolucci at gmail.com
Sat Oct 5 08:40:41 EEST 2019

Dear Dan,

I am a bit scared by what you propose. Let me summarize your procedure.

You have a bag of things: islands, settlements (by the way, what do you mean by settlement?), territories. They all have the same nature, and have borders separating them from the rest of the universe: some are bona fide, i.e. they are borders permanently (or almost so) involving some discontinuity or heterogeneity; others don’t, and they are called fiat borders. This classification created by Smith and Varzi in a famous paper is independent from time variability.

For example, an island has bona fide borders, but they may abruptly change due to natural phenomena, and Thira is a well-known example of this. A coast may be eroded by waves, sometimes very slowly and sometimes in a way perceptible by a human. A glacier is a bona fide object because its borders are defined by the intrinsic difference between the ice and the terrain, but it changes its shape in time, being larger in the winter compared to the summer.
In the paper by Smith and Varzi introducing such concepts, the North Sea is mentioned as a fiat object although it is reasonably stable in time; actually all fiat objects tend to be variable in time due to their social/human definition.

Further, time independence is not the same as time absence: Place is a concept based on time absence. To keep the integrity of your bag content, Place should be a 4D cylinder not varying along the t-axis. According to the current CRM definition, it is instead timeless. How would you manage the above mentioned case of Thira? It starts existing as a Place, but after the eruption it becomes a Space-Time Volume?

Unfortunately I have no clean solution to offer. The only escape way I see tonight is to illegally associate to every Place a Space-time volume, also called Place, which has identical time sections to the Place at any time t, from the Big Bang to the end of the universe we could say; but no CRM property exists that allows associating the cross-section of a 4D Space-time volume at a given time t0 to the corresponding 3D region, a Place. In other words, Places would (always?) be projections (P161) of Space-time volumes; when the latter does not change in time, i.e. it is a 4D cylinder, it is also called a Place. 

This proviso makes your distinction not illogical any more, but just illegal; which is a substantial step forward.
Then, variability in time is a matter of granularity, and may be well chosen by you according to the scope and purpose of your modeling. 

I am sending you separately some considerations on Space-time volumes - which are of course available to all the interested ones. A good read for the weekend.



Prof. Franco Niccolucci
Director, VAST-LAB
PIN - U. of Florence
Scientific Coordinator

ACM Journal of Computing and Cultural Heritage (JOCCH) 

Piazza Ciardi 25
59100 Prato, Italy

> Il giorno 4 ott 2019, alle ore 21:46, Dan Matei <Dan at cimec.ro> ha scritto:
> Hi friends,
> In my legacy data, beside precise geographical Places (polygons, lines, points), of course I have 
> named territories.
> Well, all Places are time-dependent: they are all post Big-Bang :-) But in order to simplify my 
> life, I am tempted to model as E53_Place the bona fide spatial objects:
> •	the "history-independent" places (e.g. Island of Crete, North America)
> •	the settlements (yes, a brutal simplification as bona fide objects)
> and as E92_SpaceTime_Volume the fiat spatial objects:
> •	the territories of (extended) administrative units (counties..., countries, empires).
> A few territories are stable in space AND time, e.g. Czechoslovakia, almost (1918-1993, with the 
> WW2 caesura), but others... Think of the Habsburg Empire.
> Of course, there are "special" cases of almost identity, as "Malta" (the island) and the territory 
> of "the Republic of Malta" (1964-), but I could live with them :-)
> What do you think ? could that be a reasonable enough decision ?
> Dan
> _____________________________________________________________
> Dan Matei, bibliograf
> Institutul Național al Patrimoniului, Secția Biblioteci Digitale
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