Posted by Stephen Stead
18/07/2014
Dear CRM-SIG
I would like to suggest the following revision to the scope note for E73 Information
Object. Its intention is to specifically mention “named graphs” as being instances of
E73 Information Object. As we look at implementation of the CRM it is becoming
increasingly obvious that “named graphs” are going to be a particularly useful tool, it
would therefore seem handy if we explicitly mentioned that they live in E73!
Best regards
SdS
Current Scope Note
E73 Information Object
Subclass of:
E89 Propositional Object
E90 Symbolic Object
Superclass of:
E29 Design or Procedure
E31 Document
E33 Linguistic Object
E36 Visual Item
Scope note:
This class comprises identifiable immaterial items, such as a poems,
jokes, data sets, images, texts, multimedia objects, procedural
prescriptions, computer program code, algorithm or mathematical
formulae, that have an objectively recognizable structure and are
documented as single units.
An E73 Information Object does not depend on a specific physical
carrier, which can include human memory, and it can exist on one or
more carriers simultaneously.
1
Instances of E73 Information Object of a linguistic nature should be
declared as instances of the E33 Linguistic Object subclass. Instances
of E73 Information Object of a documentary nature should be declared
as instances of the E31 Document subclass. Conceptual items such as
types and classes are not instances of E73 Information Object, nor are
ideas without a reproducible expression.
Examples:
 image BM000038850.JPG from the Clayton Herbarium in London
 E. A. Poe's "The Raven"
 the movie "The Seven Samurai" by Akira Kurosawa
 the Maxwell Equations
Properties:
Revised Scope Note
E73 Information Object
Subclass of:
E89 Propositional Object
E90 Symbolic Object
Superclass of:
E29 Design or Procedure
E31 Document
E33 Linguistic Object
E36 Visual Item
Scope note:
This class comprises identifiable immaterial items, such as a poems,
jokes, data sets, images, texts, multimedia objects, procedural
prescriptions, computer program code, algorithm or mathematical
formulae, that have an objectively recognizable structure and are
documented as single units. The encoding structure known as a
“named graph” also falls under this class, so that each “named graph”
is an instance of an E73 Information Object.
2
An E73 Information Object does not depend on a specific physical
carrier, which can include human memory, and it can exist on one or
more carriers simultaneously.
Instances of E73 Information Object of a linguistic nature should be
declared as instances of the E33 Linguistic Object subclass. Instances
of E73 Information Object of a documentary nature should be declared
as instances of the E31 Document subclass. Conceptual items such as
types and classes are not instances of E73 Information Object, nor are
ideas without a reproducible expression.
Examples:
 image BM000038850.JPG from the Clayton Herbarium in London
 E. A. Poe's "The Raven"
 the movie "The Seven Samurai" by Akira Kurosawa
 the Maxwell Equations
Properties:
Posted by Øyvind Eide
23/07/2014
Dear Steve,
This sounds good to me. Do you think an example of a named graph
should be added as well?
Posted by Stephen Stead
24/07/2014
Can you think of a named graph that would be sufficiently iconic to
make a good example?
---------------------------------------------------------------------
Posted by Simon Spero
24/07/2014
The AAT might work.
I'm not entirely sure that named graphs are propositional objects as defined in the
CRM, but I think the definition is loose enough.
Named graphs are not graphs that are named; they are a tuple of an IRI (which is a
name), and graph (which is the set of propositions). If the name is a proposition, it is
not one in the graph it is associated with.
3
If Propositional objects can include parts which are not propositions then there is no
problem- though it would seem more natural to have information objects only part of
which are propositional.
That would be a bit too big a change this far down the road ; if named graphs can't fit
directly, graphs themselves would; these could be part of named graphs.
Posted by Richard Light
24/07/2014
I must say that I'm not so sure that named graphs are going to be particularly useful for
implementations of the CRM. As I understand it (and I don't claim to be an RDF expert), the idea of
quads was invented so that "naked" RDF assertions could be given a "context". The problem I have
always had with that idea is that you only get one shot at it (i.e. you can only assign one context to
any given triple).
Surely (a) we need to be able to express multiple contexts for statements made within the CRM, (b)
we have already developed a rich enough use of RDF to allow us to do so.
Posted by Simon Spero 24/07/2014
On Thu, Jul 24, 2014 at 4:03 AM, Richard Light
<richard@light.demon.co.uk> wrote:
I must say that I'm not so sure that named graphs are going to be particularly
useful for implementations of the CRM. As I understand it (and I don't claim
to be an RDF expert), the idea of quads was invented so that "naked" RDF
assertions could be given a "context". The problem I have always had with
that idea is that you only get one shot at it (i.e. you can only assign one context
to any given triple).
A triple is a true proposition*; duplicates are redundant (A and A <-> A). However,
there can be multiple speech acts asserting that the proposition is true. There are
ways of giving semantics to named graphs that enable that; however, the semantics of
named graphs were deliberately left underspecified (a decision that was not
uncontroversial).
In the end, what was published was a Working Group Note listing some of the
possibilities that were argued for - see: http://www.w3.org/TR/rdf11-datasets/ .
There are other possible semantics that named graphs might have ; for example, the
name in a named graph might denote some graph containing the reified forms of the
statements in the graph part of the named graph. This differs from the quotational
semantics given in §3.7 of the note cited above given the presence of blank nodes ("one does not simply quantify into quoted contexts!").
4
Since the CRM does not require that the propositional content of an propositional
object be true, it might be possible to avoid these questions by dealing with Graphs
(as sets of propositions), and assertions of the contents of those Graphs directly .
Simon
* which is why, now that RDF 1.1 make any triple will an ill-typed literal false, any
graph that contains such triple is inconsistent.
Posted by Martin 25/07/2014
Dear Simon,
I am not sure if I understand your argument. Any informartion object might quite
well have a name.
In particular it has an identity as a unit, and being a unit is not equal to any of its
propositions. This is probably the same as modelling the Named Graphs as tuples
(name, set).
I'd however question your statement:
"Named graphs are not graphs that are named; they are a tuple..." I'd say, they are
graphs that are named in the framework of RDF encoding using a particular syntax.
They can be modelled mathematically as tuples...."
A tuple (name, set) is equally meaningless out of the context to which such a model
refers to. It could be anything you would like to use it for. That's maths. Isn't it?
In other words, yes, an information object has not only content. It has a unity, an
identity, and even a provenance.
The question is, if two information objects are identical if the contain the same set of
symbols or propositions but have different provenance. This is particularly a problem
with very small information objects.
Posted by Martin 25/07/2014
Dear Richard,
5
At least in the implementations we use one triple can be in any number of graphs,
even nested ones (SESAME, Virtuoso, OWLIM).
The point Steve is making here that Named Graphs are the only way in which facts in
a database can be described as explicit content of multiple(!) information objects
which are described (creation etc.) in the same system. There is no other choice for
implementing argumentation systems which explicitly describe premises and
conclusions as propositions in the database.
On 24/7/2014 11:03 πμ, Richard Light wrote:
I must say that I'm not so sure that named graphs are going to be particularly
useful for implementations of the CRM. As I understand it (and I don't claim
to be an RDF expert), the idea of quads was invented so that "naked" RDF
assertions could be given a "context". The problem I have always had with
that idea is that you only get one shot at it (i.e. you can only assign one context
to any given triple).
Surely (a) we need to be able to express multiple contexts for statements made
within the CRM, (b) we have already developed a rich enough use of RDF to
allow us to do so.
Richard
On 24/07/2014 05:57, Simon Spero wrote:
The AAT might work.
I'm not entirely sure that named graphs are propositional objects as
defined in the CRM, but I think the definition is loose enough.
Named graphs are not graphs that are named; they are a tuple of an IRI
(which is a name), and graph (which is the set of propositions). If the
name is a proposition, it is not one in the graph it is associated with.
If Propositional objects can include parts which are not propositions
then there is no problem- though it would seem more natural to have
information objects only part of which are propositional.
That would be a bit too big a change this far down the road ; if named
graphs can't fit directly, graphs themselves would; these could be part
of named graphs.
I am not sure if "The encoding structure known as a “named graph” also falls under
this class, so that each “named graph” is an instance of an E73 Information Object."
is the right way to say it.
6
May be better
"information encoded as named graphs may represent instances of E73 Information
object including an explicit representation of contents".
Since it is an encoding construct, it may represent other things as well. In a sense, it
is trivial that any RDF File is an information object, but it is not trivial if a part of the
content of an RDF File represents (,not "is",) an information object in its own right. I
would rather put that at the end of the scope note as an implementation note.
---------------------------------------------------------------------------------------------------------------------------------------
Posted by Simon Spero
26/07/2014
To clarify (or obfuscate),
The term "named graph", as used in RDF, is defined in section 4 of the RDF
1.1 Concepts and Abstract Syntax Recommendation.
Each named graph is a pair consisting of an IRI or a blank node (the graph
name), and an RDF graph.
[...]
NOTE
Despite the use of the word “name” in “named graph”, the graph name is not
required to denote the graph. It is merely syntactically paired with the graph.
RDF does not place any formal restrictions on what resource the graph name
may denote, nor on the relationship between that resource and the graph. A
discussion of different RDF dataset semantics can be found in [RDF11DATASETS].
I have no problems with having an entity that made of one part that is
a Propositional Object, and another part that is an IRI. The obvious
identity criteria for such an entity would include both components - two
"named graph"s with different IRI parts would be distinct.
( I also have no problem with the Cyc mereological approach to the
relationship between conceptual works and information bearing objects, so
my judgement is suspect).
Simon
7
Posted by Martin
27/07/2014
Dear Simon,
On 26/7/2014 12:41 πμ, Simon Spero wrote:
To clarify (or obfuscate),
The term "named graph", as used in RDF, is defined in section 4 of the RDF
1.1 Concepts and Abstract Syntax Recommendation.
Each named graph is a pair consisting of an IRI or a blank node
(the graph name), and an RDF graph.
[...]
NOTE
Despite the use of the word “name” in “named graph”, the graph
name is not required to denote the graph. It is merely syntactically
paired with the graph. RDF does not place any formal restrictions on
what resource the graph name may denote, nor on the relationship
between that resource and the graph. A discussion of different RDF
dataset semantics can be found in [RDF11-DATASETS].
That's clear enough
I see your point now: The Named Graph is does not give a name to the set of triples in
it, because two identical sets of triples can have different names. It is a new thing with
a name, which contains a set of triples.
I have no problems with having an entity that made of one part that is
a Propositional Object, and another part that is an IRI. The obvious
identity criteria for such an entity would include both components - two
"named graph"s with different IRI parts would be distinct.
That is the idea. I'd see the propositions as "content" or "parts" of the Named Graph.
At least implementations using reference counts for identical triples in different
Named Graphs regard them as non-identical, even if they have the same content. That
makes them suitable for us to trace provenance as we would do with information
objects. Information Objects acquire an individual history. With Named Graphs, I can
connect such a history. I could also use the Named Graph to model a belief associating with the IRI a belief value, a validity time-Span and a believing Actor.
Interesting cases are, when different people detect the same laws of nature or
mathematics. We would keep the different traditions as distinct, and eventually detect
the identity, which merges the two traditions. Otherwise we would mess up reasoning
8
about the information transfer. Also, we would mess up cases when different senses
are intended with incidentally identical phrases.
So, I'd argue, semantics of Named Graphs that bind identity to the name plus content
are indeed what we need to model information objects consisting of statements in
form of triples.
---------------------------------------------------------------------------------------------------------------------------------------
Posted by Richard Light
28/07/2014
Martin,
I thought that a major merit of the CRM was that it was an abstract model, which
could be instantiated using whatever technology was felt to be appropriate. That
being the case, I would be concerned if RDF-specific techniques were presented to
the world as the only way in which a particular challenge ("implementing
argumentation systems ...") could be tackled using the CRM. Or are you talking
specifically about RDF implementations of the CRM?
Why can't "premises and conclusions" be modelled using reification, so they can
then be given a unique URI? This is the sort of approach which the BM has
successfully deployed, as I understand it. I would be grateful if someone could
provide a really simple concrete example which shows the need for the named graph
approach.
To pick up on the suggestion of using the AAT as an example: in what way is the AAT
a named graph? Surely it's a SKOS Concept Scheme (plus)? I think it would be
impossible to give an example of a "well-known" named graph, for the reasons
Simon has been explaining.
---------------------------------------------------------------------------------------------------------
Posted by Dominic
28/07/2014
I am slightly confused about this discussion.
9
The purpose of the scope notes is to clarify the meaning of the entities and
relationships that make up the CRM. The CRM models real world things both
material and non-material.
Inclusion of a named graph example in the scope notes does not affect the technical
independence of the standard. It simple says that this is an example (in this case) of
a propositional object. We need to have examples that are practically useful and
mean something to people.
In that context it personally bothers me not whether we have an example of a
named graph or indeed other examples from other schema formats - as long as it
helps people to understand what a propositional object is (and its scope). We could
equally use examples from other data schema worlds and again it would say nothing
about the technical implementation of the CRM. None of these examples would
affect the standard in terms of its neutrality. It’s an illustrative scope note, but is not
part of the standard in the context you describe.
Examples need to be wide and varied and cater for all the different types of people
that use the CRM and want to understand how it works.
Posted by Martin
28/07/2014
Dear Richard,
On 28/7/2014 11:41 πμ, Richard Light wrote:
Martin,
I thought that a major merit of the CRM was that it was an abstract model,
which could be instantiated using whatever technology was felt to be
appropriate. That being the case, I would be concerned if RDF-specific
techniques were presented to the world as the only way in which a particular
challenge ("implementing argumentation systems ...") could be tackled using
the CRM. Or are you talking specifically about RDF implementations of the
CRM?
I share your concerns !
10
Why can't "premises and conclusions" be modelled using reification, so they
can then be given a unique URI? This is the sort of approach which the BM
has successfully deployed, as I understand it. I would be grateful if someone
could provide a really simple concrete example which shows the need for the
named graph approach.
Your are right!
Actually I see the "Named Graph" not as a particular RDF feature, but at the level of
abstraction that Simon pointed out: A set of propositions with a "historical" identity
which is not reduced to the identity of the set itself.
The CRM uses an abstract data model of classes, superclasses, properties,
superproperties etc., which is more or less the stable core of all data structures and KR
models used so far in industrial systems. We have however adopted the term
"property" from RDF, just to reduce the semantic gap for people now. Originally, we
used TELOS terms, but KIF, OIL was equally compatible.
The requirement to introduce argumentation structures into consistent graphs of
propositions is relatively new. Reification is an atomic mechanism, which does not
allow for describing that a set of propositions is believed together.
Therefore it looses an important part of the semantics of argumentation. A Named
Graph is in my mind an abstarction which subsumes reification. Reification is a
workaround using a syntax which has not foreseen the problem before. Named Graph
is a NEW logical construct not found in any other industrial KR model, and born out
of a necessity that first showed up when integrating different sources. (Before, one
could say AI just slept in a one-truth cyberworld with a god-like user or math on top
of reality).
I believe we need the Named Graph construct as a logical form, not as an RDF syntax,
if we want to integrate provenance of knowledge with the CRM. So far, we have
evidence of two real-life data structures, one is archaeological excavation records, and
another description of medieval book-bindings, which systematically register source
of evidence and concluded facts. E.g., geometric topology of stratigarphic units and
microscopic stratigraphic interface properties are used to justify chronological
sequence. In a simple model, this is atomic, in a more general, it is probabilistic
Bayesian. So, we would need a "Typed Named Graph", which restricts the
propositions in the Graph to a certain schema (topology, chronology), and then a
relationship "is evidence for" between the typed named graphs. The assertion itself
forms part of the belief implicit in the archaeological record.
If there is any logician on this mailing list, a proper formulation of such a construct
and an abstract syntax for the CRM would be great to have!!!
We will try to suggest a graphic primitive, which is a bubble around the propositions
with a "hot spot" on the perimeter.
Suggestions most welcome!
11
To pick up on the suggestion of using the AAT as an example: in what way is
the AAT a named graph? Surely it's a SKOS Concept Scheme (plus)? I think
it would be impossible to give an example of a "well-known" named graph,
for the reasons Simon has been explaining.
Named Graphs are new, so none is really "well known", but I would regard a
skosified AAT as a Named Graph, as well as all the RDF junks for LoD, once RDF
regards any RDF file as a Named Graph. The only condition is, that two RDF Files
with the same content and different URI are not regarded as being identical
(owl:same_as).
Posted by Richard Light 28/07/2014
Martin,
Thanks you for this: I now have a much better idea of what you are trying to
express. I can also now see how the AAT is relevant to the discussion: it is precisely a
set of propositions with an identity, or (to use SKOS terminology) a Concept
Scheme. (However, I can't see the AAT being cited as justification for an assertion or
set of assertions.) Is your idea of a "Named Graph" close to that of a Concept
Scheme?
----------------------------------------------------------------------------------------------------------------------------
Posted by Richard
29/07/2014
Martin,
Thank you for this: I now have a much better idea of what you are trying to
express. I can also now see how the AAT is relevant to the discussion: it is precisely a
set of propositions with an identity, or (to use SKOS terminology) a Concept
Scheme. (However, I can't see the AAT being cited as justification for an assertion or
set of assertions, so maybe it's not that pertinent an example.)
However, the AAT as a concept scheme is identified by the URI:
http://vocab.getty.edu/aat/
12
which yields a web page when invoked normally, and redirects to:
http://vocab.getty.edu/download/rdf?uri=http://vocab.getty.edu/aat/
when RDF is requested in the HTTP Accept header. Every concept within AAT
contains an assertion that it is skos:inScheme AAT.
So, in what way would you create a Named Graph (in your sense) for the AAT? What
URI would you associate with each triple in the concept scheme? And what practical
benefit does this give you, that simply using the URL quoted above doesn't give you?
----------------------------------------------------------------------------------------------------------------
Posted by Christian Emil
29/07/2014
Dear all,
It should be unproblematic to add an RDF example to the scope note
of E73. This is just one example among others.
RDF is perhaps not the ideal solution to implement systems with
deduction.
Between a set of premises and a conclusion there must of course be a
series of applications of deduction rules. The premises are a set of
facts (that is assumed to be true). In a RDF triple store (heap)
containing more facts than relevant (or perhaps inconsistent with)
the facts used in the deduction, the set of facts used as the
premises must be identified. I assume it is here the named graphs are
needed.
To check results in hypothetic-deductive science (which I believe
this is all about) , one needs a) to check the way (deduction) from
the premises to the conclusion to see if it is valid under the
assumption that the premises are and b) check if the premises (the
set of facts) are true/valid.
Last time I worked with this was in the previous high days of AI in
the end of the 1980ies. At that time the focus was not so much on
facts but on deduction (type theory, lambda calculus, lisp, prolog).
The current RDF focus on facts obscure the logical focus.
13
Posted by Martin
29/07/2014
Dear Christian-Emil,
On 29/7/2014 10:00 πμ, Christian-Emil Smith Ore wrote:
Dear all,
It should be unproblematic to add an RDF example to the scope
note of E73. This is just one example among others.
RDF is perhaps not the ideal solution to implement systems with
deduction.
Your comments well taken - but I did not want to talk about AI and binary logic at
all, nor about code running conclusions on its own. Belief values can be anything up
to gut feelings. What I wanted to talk about is monitoring human-made inferences S/W generated inferences only being a special kind of which are modified by belief
values in the code itself. I agree with you that such as system must be able to
distinguish between different parts of the graph.
The total of propositions in a triple store using CRM is expected to be globally
inconsistent, and anyhow the belief values are not adequately represented. Bayesian
networks are among the kinds of reasoning users would apply - they do not fit with AI
languages anyhow.
Therefore RDF should be sufficient to represent the chaining of arguments ?
(see also Doerr, M., Kritsotaki, A., & Boutsika, A. (2011). Factual argumentation - a
core model for assertions making. Journal on Computing and Cultural Heritage
(JOCCH) , 3(3), 34, New York, NY, USA : ACM)
In general, you can correctly conclude from a correct premise a wrong conclusion, if
your argument is probabilistic. You can conclude from a wrong premise a correct
conclusion - by chance, and you can make a wrong inference from a correct premise
resulting in a correct conclusion , as many proofs in mathematics. I believe a minimal
formal system for cultural discourse would be a combination of modal logic with
unknown values.
I agree that "the current RDF focus on facts obscures the logical focus"
---------------------------------------------------------------------------------------------------
Posted by Martin 29/07/2014
Hi Richard,
On 29/7/2014 12:06 πμ, Richard Light wrote:
Martin,
Thank you for this: I now have a much better idea of what you are trying to
express. I can also now see how the AAT is relevant to the discussion: it is
precisely a set of propositions with an identity, or (to use SKOS terminology)
a Concept Scheme. (However, I can't see the AAT being cited as justification
for an assertion or set of assertions, so maybe it's not that pertinent an
example.)
14
However, the AAT as a concept scheme is identified by the URI:
http://vocab.getty.edu/aat/
which yields a web page when invoked normally, and redirects to:
http://vocab.getty.edu/download/rdf?uri=http://vocab.getty.edu/aat/
when RDF is requested in the HTTP Accept header. Every concept within
AAT contains an assertion that it is skos:inScheme AAT.
So, in what way would you create a Named Graph (in your sense) for the
AAT? What URI would you associate with each triple in the concept
scheme?
http://vocab.getty.edu/aat/
And what practical benefit does this give you, that simply using the URL
quoted above doesn't give you?
You can upload the AAT into a triple store and still know this is the same AAT...
An example of a "well known" graph will always have that problem - it is defined
somewhere else.
In the CRM, we do not require examples to be well known. We can create a small
TRIG file.
The whole point of a Named Graph is distinguishing a bunch of propositions within a
database (triple store,graph database...). If the propositions are still on the Getty
server, I cannot run a transitive closure etc. on its content.
You can regard the whole LoD space as a big triple store, but you cannot run a query
against it up to now.
This part of LoD is still a bit in the science fiction area - at least from the point of
view of industrial application.
Distributed querying still poses theoretical questions and serious performance issues.
I'd guess some 20 years to become reality, if ever. The "if ever" comes from my
concerns how you can manage such a space without controlled provenance of
knowledge with all its ramifications.
-----------------------------------------------------------------------------------------------
Posted by Martin 29/07/2014
Dear All,
If I am not mistaken, this is an example of a Nemaed Graph:
<uuid:5f26a9bb-85ff-453b-8cd2-60717ceb54f6> {
15
<uuid:198509e3-dc91-4553-aead-23504f05f201> <http://www.cidoc-crm.org/cidoccrm/P50_has_current_keeper> <www.britishmuseum.org/>.
}
??
Posted by Barry Norton 29/07/2014
Yes, that’s a single-triple named graph defined in TriG (though, again, uuid: is not the correct
scheme for RFC 4122 compliant UUID-based URNs)
B
Posted by Richard Light 29/07/2014
On 29/07/2014 13:44, martin wrote:
So, in what way would you create a Named Graph (in your sense) for the
AAT? What URI would you associate with each triple in the concept
scheme?
http://vocab.getty.edu/aat/
And what practical benefit does this give you, that simply using the URL
quoted above doesn't give you?
You can upload the AAT into a triple store and still know this is the same
AAT...
An example of a "well known" graph will always have that problem - it is
defined somewhere else.
In the CRM, we do not require examples to be well known. We can create a
small TRIG file.
The whole point of a Named Graph is distinguishing a bunch of propositions
within a database (triple store,
graph database...). If the propositions are still on the Getty server, I cannot run
a transitive closure etc. on its
content.
OK, thanks for your patience: I see now.
-------------------------------------------------------------------------------------------------------
Posted by Simon Spero 29/07/2014
If the propositions in a named graph are treated the same way that propositions in
other propositional objects then the CRM need make no commitment as to their truth.
16
Completely false "documents" that claimed to describe reality are still at the least
information objects.
Also, to clarify: RDF and RDFS are based in classical logic, as is OWL, which is the
description logic SROIQ(D).
RDF triples are ground terms that, if accepted, are axioms; if there are logical
inconsistencies this inconsistency will cause clashes (most OWL reasoners are tableau
based).
Posted by Martin 30/ 07/2014
Dear Simon,
On 29/7/2014 7:34 μμ, Simon Spero wrote:
If the propositions in a named graph are treated the same way that propositions
in other propositional objects then the CRM need make no commitment as to
their truth.
Completely false "documents" that claimed to describe reality are still at the
least information objects.
This is indeed how I perceive the CRM and the next step in integrated knowledge
management!
Belief values, of any kind, are orthogonal to propositions. Since real world science
and scholarship is much
more subtle in belief value than formal logic, and the actual nature of conviction
formation by humans is still an open research question, but empirically successful
(otherwise we had no aeroplanes), a reasonable
scientific and scholarly information service must separate propositions from implicit
truth values in the long term.
I see the near future as monitoring all information back to the evidence of knowledge
it is grounded in, as a phenomenological approach, which models and implements
what any good researcher so far should do anyhow,
but cannot in current information aggregation system.
Also, to clarify: RDF and RDFS are based in classical logic, as is OWL, which
is the description logic SROIQ(D).
RDF triples are ground terms that, if accepted, are axioms; if there are logical
inconsistencies this inconsistency will cause clashes (most OWL reasoners are
tableau based).
Yes! The implicit logic in RDF/RDFS is however minimal and categorical:
subsumption and inheritance of properties. Applied to the concepts in the CRM only,
17
we would not question these on a regular base. To overcome practically the intrinsic
fuzziness of the concepts in the CRM, we normally adopt a "recall over precision"
attitude in the definition, classification and querying (everything that "could be an E7
Activity" should be classified as an E7 Activity).
All other theories expressed in RDF do not need to be logically consistent in a CRM
implementation (multiple fathers etc. ).
The use of OWL rules in a database is practically prohibitive: It inhibits data entry
without adequate diagnostics to the user about the reasons of failure. It prevents
storing alternative opinions, one of the fundamenatl requirements for CRM-based
aggregation services.
Posted by Christian Emil 31/07/2014
This is an interesting discussion, but somewhat distant from the
question "Should the scope note for E73 Information Object be extend
with an example showing that a named graph in rdf represents an
instance of E73 Information Object?". In my view this is
unproblematic.
Propositional objects and hence information objects are described in
the CRM as: " This class comprises immaterial items, including but
not limited to stories, plots, procedural prescriptions, algorithms,
laws of physics or images that are, or represent in some sense, sets
of propositions about real or imaginary things and that are
documented as single units or serve as topic of discourse".
Every instance of the class(es) represents a proposition/statement
constructed by a human. (Thus it is not a Platonic object existing
before and independently of humans for those interested in the
formalist<->Platonist debate) . Even in mathematics important proofs
are not necessarily carried out in all formalistic details. The four
colour problem was partly solved by computerized proofs, but nobody
cared to proof the correctness of the programs.
RDF(S): In principle (and in some implementations) rdf triple stores
are basically equal to a relational database with one table with
three (four for named graphs?) columns. With the old Z39.50 protocol
added one would have a variant of linked data or semantic web. So
there is nothing new here but a much more handy language to express
pieces information and how they interlink. From a logician point of
view RDF(S) is an implementation /interpretation technique on the
model level.
So what is meant by 'classic" in the "RDF(S) is based on classic
logic"?.
Posted by Martin
31/07/2014
Dear Christian-Emil,
On 31/7/2014 10:03 πμ, Christian-Emil Smith Ore wrote:
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This is an interesting discussion, but somewhat distant from
the question "Should the scope note for E73 Information Object
be extend with an example showing that a named graph in rdf
represents an instance of E73 Information Object?". In my view
this is unproblematic.
Propositional objects and hence information objects are
described in the CRM as: " This class comprises immaterial
items, including but not limited to stories, plots, procedural
prescriptions, algorithms, laws of physics or images that are,
or represent in some sense, sets of propositions about real or
imaginary things and that are documented as single units or
serve as topic of discourse".
Every instance of the class(es) represents a
proposition/statement constructed by a human. (Thus it is not a
Platonic object existing before and independently of humans
for those interested in the formalist<->Platonist debate) .
Even in mathematics important proofs are not necessarily
carried out in all formalistic details. The four colour problem
was partly solved by computerized proofs, but nobody cared to
proof the correctness of the programs.
Yes, context cannot be ignored. We have to perceive all information
as ways to communicate about trust in knowledge between humans.
RDF(S): In principle (and in some implementations) rdf triple
stores are basically equal to a relational database with one
table with three (four for named graphs?) columns.
"Quad Stores", yes.
With the old Z39.50 protocol added one would have a variant of
linked data or semantic web. So there is nothing new here but a
much more handy language to express pieces information and how
they interlink. From a logician point of view RDF(S) is an
implementation /interpretation technique on the model level.
So what is meant by 'classic" in the "RDF(S) is based on
classic logic"?.
As I understand, relational databases do not know links (joins are
arbitrary), subsumption and inheritance.This and the Relational logic
are described in FOL?
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