ISO/IEC 13250-5:2015

INTERNATIONAL ISO/IEC
STANDARD 13250-5
First edition
2015-04-01

Information technology — Topic Maps —
Part 5:
Reference model
Technologies de l'information — Plans relatifs à des sujets —
Partie 5: Modèle de réference




Reference number
ISO/IEC 13250-5:2015(E)
©
ISO/IEC 2015

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ISO/IEC 13250-5:2015(E)

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ISO/IEC 13250-5:2015(E)
Contents Page
Foreword . iv
Introduction . v
1 Scope . 1
2 Subjects . 1
3 Subject Proxies and Maps . 1
4 Ontological Commitments . 2
5 Navigation . 3
6 Merging . 4
7 Constraints . 5
8 Map Legends . 6
9 Conformance . 6
Annex A (normative) Path Language . 7
Annex B (informative) Notation . 11
Bibliography . 12
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ISO/IEC 13250-5:2015(E)
Foreword
ISO (the International Organization for Standardization) and IEC (the International Electrotechnical
Commission) form the specialized system for worldwide standardization. National bodies that are members of
ISO or IEC participate in the development of International Standards through technical committees
established by the respective organization to deal with particular fields of technical activity. ISO and IEC
technical committees collaborate in fields of mutual interest. Other international organizations, governmental
and non-governmental, in liaison with ISO and IEC, also take part in the work. In the field of information
technology, ISO and IEC have established a joint technical committee, ISO/IEC JTC 1.
The procedures used to develop this document and those intended for its further maintenance are described
in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the different types of
document should be noted. This document was drafted in accordance with the editorial rules of the
ISO/IEC Directives, Part 2 (see www.iso.org/directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO and IEC shall not be held responsible for identifying any or all such patent rights. Details of any
patent rights identified during the development of the document will be in the Introduction and/or on the ISO
list of patent declarations received (see www.iso.org/patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation on the meaning of ISO specific terms and expressions related to conformity assessment,
as well as information about ISO's adherence to the WTO principles in the Technical Barriers to Trade (TBT)
see the following URL: Foreword ‐ Supplementary information
ISO/IEC 13250-5 was prepared by Joint Technical Committee ISO/IEC JTC 1, Information technology,
Subcommittee SC 34, Document description and processing languages.
ISO/IEC 13250 consists of the following parts, under the general title Information technology — Topic Map:
— Part 2: Data model
— Part 3: XML syntax
— Part 4: Canonicalization
— Part 5: Reference model
— Part 6: Compact syntax
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ISO/IEC 13250-5:2015(E)
Introduction
The Topic Maps family of standards is designed to facilitate the gathering of all the information about a subject
at a single location. The information about a subject includes its relationships to other subjects; such
relationships may also be treated as subjects (subject-centric).
ISO/IEC 13250-2:2006 [1] provides a foundation for syntaxes and notations, such as those defined in ISO/IEC
13250-3 Topic Maps XML Syntax [2] and ISO/IEC 13250-4 Topic Maps Canonicalization [3]. Of necessity,
ISO/IEC 13250-2:2006 [1] makes ontological commitments in terms of how particular subjects are identi_ed
(topics, associations, occurrences), what properties are required, the tests to be used to determine whether
two or more proxies represent the same subject, and other matters.
This part of ISO/IEC 13250 defines TMRM (Topic Maps Reference Model), which is more abstract and has
fewer ontological commitments. Its purpose is to serve as a minimal, conceptual foundation for subject-centric
data models such as ISO/IEC 13250-2:2006 [1], and to supply ontologically neutral terminology for disclosing
these. It de_nes what is required to enable the mapping of different subject-centric data models together to
meet the overall goal of the Topic Maps standards, that each subject has a single location for all the
information about it.
TMRM also provides a formal foundation for related Topic Maps standards such as the ISO/IEC 19756 Topic
Maps Constraint Language (TMCL) [4].
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INTERNATIONAL STANDARD                                 ISO/IEC 13250-5:2015(E)
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Information technology — Topic Maps — Part 5: Reference
Model
1 Scope
This part of ISO/IEC 13250 species a formal model for subject maps, minimal access func-
tionality and information retrieval from subject maps and a constraint framework governing the
interpretation of subject maps.
Particular formalisms to constrain subject maps are not covered by this part of ISO/IEC 13250.
2 Subjects
A subject is dened in the Topic Maps family of standards as something which '[.] can be
anything whatsoever, regardless of whether it exists or has any other specic characteristics,
about which anything whatsoever may be asserted by any means whatsoever' (ISO/IEC 13250-
2:2006 5.3.1). According to the TMRM, there is only one representative for subjects: subject
proxies (proxies).
3 Subject Proxies and Maps
Proxies consist of properties. These are key/value pairs which|in turn|may contain references
to other proxies. This recursive relationship is dened via two postulated sets. One is the nite
set of proxy labels,L. The second set isV, a nite set of values. It contains values (such as
numbers, strings, etc.), and all the labels inL.
A property is the pairhk;vi2LV. The rst component of this pair is called the key, the other
the value of the property. The set of all such properties is denoted asP. Keys in properties are
always labels, the values in properties may be labels or any other value from the value setV.
EXAMPLE 1 Given the label shoesize and the integer 43, thenhshoesize;43i is a property.
A proxy is a nite set of properties,fp ;:::;p g, with p 2P (see Fig. 1). The multiset of all
1 n i
keys of a proxy x is retrievable via the function keys(x), i.e. keys can occur more than once in
a proxy with dierent values. The multiset of all values is values(x). Particular values may
appear more than once in one proxy.
EXAMPLE 2 A particular person may be represented by the following proxy:fhshoesize;43i;
hbeardcolor;whitei;hbeardlength;verylongig
1
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ISO/IEC 13250-5:2015(E)
Figure 1 { Proxy Structure
P
The set of all proxiesX is the set of all subsets ofP,X = 2 .
The connection between proxies and their labels is modeled with a partial, injective function
~:X7!V. It returns the label for a given proxy x whereby two dierent proxies never share the
same label. The function is extended to values in that v~ =v.
NOTE 1 A proxy is dened by the totality of its properties. Individual properties can provide a basis
for mapping multiple proxies of the same subject to each other.
NOTE 2 One proxy may contain several properties which all share the same key but have dierent
values; or share the same value, but have diering keys.
A subject map (map) is a nite set of proxies. The set of all such maps is denoted asM. As
0
maps are simply sets of proxies, generic merging of maps is achieved via set union, m[m .
NOTE 3 The model of subject maps described herein assumes no particular implementation technology
or strategy.
4 Ontological Commitments
This part of ISO/IEC 13250 deliberately leaves undened the methods whereby subject proxies
are derived or created. No specic mechanism of subject identication is inherent in or mandated
by this part of ISO/IEC 13250, nor does it predene any subject proxies.
NOTE 1 Any subject proxy design choices would be specic to a particular application domain and
would exclude equally valid alternatives that might be appropriate or necessary in the contexts of various
requirements.
Two types of relationships, ako (subclass of) and isa (instance of), are dened. These predicates
are always interpreted relative to a given map m:
0
a) Two proxies c;c can be in a subclass-superclass relationship, ako  mm. In such a
m
0 0
case, the same relationship can be stated either c is a subclass of c or c is a superclass of
c.
ako is re
exive and transitive. Re
exive means that any proxy is a subclass of itself,
m
regardless whether the proxy is used as a class in the map or not: x ako x for all x2m.
m
0 00
Transitive means that if a proxy c is a subclass of another, c , and that subclasses c , then
00 0 0 00 00
c is also a subclass of c , i.e. if c ako c and c ako c then also c ako c must be true.
m m m
2
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ISO/IEC 13250-5:2015(E)
NOTE 2 Circular subclass relationships may exist in a map.
b) Two proxies a;c can be in an isa relationship, isa  mm. In such a case, the same
m
relationship can be stated either a is an instance of c or c is the type of a.
The isa relationship is non-re
exive, i.e. x isa x for no x2 m, so that no proxy can be
m
an instance of itself. Additionally, whenever a proxy a is an instance of another c, then a
0 0
is an instance of any superclass of c: if x isa c and c ako c , then x isa c is true.
m m m
NOTE 3 Other denitions of the above relationships are possible with dierent properties than dened
by the TMRM. Such denitions would appear in legends and would be distinguished from those dened
in the TMRM.
NOTE 4 This part of ISO/IEC 13250 does not mandate any particular way of representing such rela-
tionships inside a map. One option is to model such a relationship simply with a property using a certain
key (say type). An alternative way is to provide a proxy for each such relationship. Such relationship
proxies could, for example, have properties whose keys are instance andclass, or respectively subclass
and superclass.
5 Navigation
Given a mapm and particular proxiesx;y2m in it, the following primitive navigation operators
are dened:
a) A postx operator# to return the multiset of all local keys of a given proxy:
x# =keys(x) (1)
b) A postx operator" to retrieve the multiset of remote keys of a proxy inside m. These
m
are those where the given proxy (more precisely its label) is the value in another proxy:
x" = [kj9y2m:hk;x~i2y] (2)
m
This is easily generalized to an operator for all values:
v" = [kj9y2m:hk;v~i2y] (3)
m
c) A postx operator!k to retrieve the multiset of local values for a particular key k2L:
x!k = [vj9hk;vi2x] (4)
Using the predicate ako the operator can be generalized to honor subclasses of the key k:
m
 0 0
x! k = [vj9hk;vi2x: k ako k] (5)
m m
d) A postx operator k which navigates to all proxies in the given map which use a given
m
value v together with a certain key k2L:
v k = [x2mj9hk;v~i2x] (6)
m
Using the predicate ako the operator can be generalized to honor subclasses of the key k:
m
 0 0
v k = [x2mj9hk;v~i2x: k ako k] (7)
m m
3
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ISO/IEC 13250-5:2015(E)
It is straightforward to generalize all these navigation operators on individual proxies and values
to multisets of them. As a consequence the result of one postx can be used as startpoint for
another postx, enabling the building of postx chains. This primitive path language is denoted
asP .
M
NOTE 1 P only serves as a minimal baseline for functionality to be provided by conforming imple-
M
mentations. It can be also used as the basis for a formal semantics for higher-level query and constraint
languages. Annex A describes one.
6 Merging
Generic merging of maps only combines two (or more) proxy sets. Application-specic merging
includes a second aspect. A mechanism has to be found to state whether|in a given map|two
proxies are regarded to be about the same subject. Then all such equivalent proxies have to be
actually merged.
NOTE 1 How subject sameness is determined and how the actual proxy merging is eectively done is
not constrained by this part of ISO/IEC 13250. Such a process may be dened as having inputs that
consist only of the proxies to be merged. Alternatively, the inputs may also include other information
that may appear either inside the map or elsewhere in the merging process's environment.
NOTE 2
...