[Crm-sig] Homework Issue 288

[Martin Doerr]

Dear All,

Here my guidelines:


  Guidelines for using P82a, P82b, P81a, P82b

Jan 7, 2018

The range of properties "P81_ongoing_throughout" and 
"P82_at_some_time_within" isdefined in the CRM as E61 
<#_E61_Time_Primitive> Time Primitive, i.e., (closed, contiguous) 
intervals on the natural time dimension in which we live.

Since the E61 Time Primitive of the CRM cannot directly be implemented 
in RDF databases, we define in the official RDF implementation of the 
CIDOC CRM four properties replacing P81 and P82 adequately using 
xsd:dateTime.

Property P81 describes the maximum known temporal extent of an E52 
Time-Span, i.e. the extent it is ongoing throughout. It is replaced in 
this RDF version by the property "P81a_end_of_the_begin"and 
"P81b_begin_of_the_end", to be used together.

"P81a_end_of_the_begin" should be instantiated as the earliest point in 
time the user is sure that the respective temporal phenomenon is indeed 
ongoing. We call it “end_of_the_begin”, because it also constitutes an 
upper limit to the end of the indeterminacy or fuzziness of the begin of 
the described temporal phenomenon.

"P81b_begin_of_the_end" should be instantiated as the latest point in 
time the user is sure that the respective temporal phenomenon is indeed 
ongoing. We call it “begin_of_the_end”, because it also constitutes a 
lower limit to the begin of the indeterminacy or fuzziness of the end of 
the described temporal phenomenon.

It is correct to assign the same value to P81a_end_of_the_begin and 
P81b_begin_of_the_end, if no other positive knowledge exists. It is also 
correct not to instantiate P81 for a time span, if no respective 
evidence is known.

If a respective reasoning is installed, and no evidence exists that the 
phenomenon was definitely ongoing at any point in time, one may use a 
value for P81a_end_of_the_begin greater than for P81b_begin_of_the_end, 
indicating that the indeterminacy of knowledge (not of being) of the 
begin overlaps with the indeterminacy of knowledge (not of being) for 
the end [see Christian-Emil Ore XXX].

If a value for P81a_end_of_the_begin is given with a precision less than 
that of xsd:dateTime, such as in days or years, the implementation 
should “round it up” to the last instant (second) of this time 
expression, e.g. 1971 = Dec 31 1971 23:59:59. Respectively, if a value 
for P81b_begin_of_the_end is given with a precision less than that of 
xsd:dateTime, such as in days or years, the implementation should “round 
it down” to the last instant (second) of this time expression, e.g. 1971 
= Jan 1 1971 0:00:00. If values are needed that are not within the range 
or precision of xsd:dateTime, e.g., for paleontology, this property 
should be extended with another, suitable data type.

Property P82 describes the narrowest known outer bounds of the temporal 
extent of an E52 Time-Span, i.e. the extent it is ongoing “at some time 
within” this interval. It is replaced in the official RDF version by the 
properties "P82a_begin_of_the_begin" and "P82b_end_of_the_end", to be 
used together.

" P82a_begin_of_the_begin " should be instantiated as the latest point 
in time the user is sure that the respective temporal phenomenon is 
indeed not yet ongoing. We call it “begin_of_the_begin”, because it also 
constitutes a lower limit to the begin of the indeterminacy or fuzziness 
of the begin of the described temporal phenomenon.

" P82b_end_of_the_end " should be instantiated as the earliest point in 
time the user is sure that the respective temporal phenomenon is indeed 
no more ongoing. We call it “end_of_the_end”, because it also 
constitutes an upper limit to the end of the indeterminacy or fuzziness 
of the end of the described temporal phenomenon.

It is not correct to assign the same value to P82a_begin_of_the_begin 
and P82b_end_of_the_end. If a value for P82a_begin_of_the_begin is given 
with a precision less than that of xsd:dateTime, such as in days or 
years, the implementation should “round it down” to the last instant 
(second) of this time expression, e.g. 1971 = Jan 1 1971 0:00:00. 
Respectively, if a value for P82b_end_of_the_end is given with a 
precision less than that of xsd:dateTime, such as in days or years, the 
implementation should “round it up” to the last instant (second) of this 
time expression, e.g. 1971 = Dec 31 1971 23:59:59.

It must always hold that the value for P82a_begin_of_the_begin is less 
than P82b_end_of_the_end, P81a_end_of_the_begin and P81b_begin_of_the_end.

It must always hold that the value for P82b_end_of_the_end is greater 
than P82b_end_of_the_end, P81a_end_of_the_begin and P81b_begin_of_the_end.

P82a_begin_of_the_begin and P82b_end_of_the_end should always be 
assigned a value to for any past phenomenon, albeit unrealistically far 
away from reality. It is an error to associate any quality of positive 
knowledge with these values. The scholarly practice not to give any 
outer bounds for an event, because it is, for instance, not known down 
to a precision of three years, is not helpful for automated reasoning. 
In that case, the machine may regard that the event has possibly 
happened at the time of the dinosaurs.

Please improve.

Cheers,

Martin

-- 
--------------------------------------------------------------
  Dr. Martin Doerr              |  Vox:+30(2810)391625        |
  Research Director             |  Fax:+30(2810)391638        |
                                |  Email: martin at ics.forth.gr |
                                                              |
                Center for Cultural Informatics               |
                Information Systems Laboratory                |
                 Institute of Computer Science                |
    Foundation for Research and Technology - Hellas (FORTH)   |
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                                                              |
              Web-site: http://www.ics.forth.gr/isl           |
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