The document discusses the key aspects of thesauri including their purpose, structure, types of relationships displayed, and evaluation criteria. Specifically, it notes that a thesaurus provides a standardized vocabulary for information retrieval by displaying hierarchical (e.g. broader and narrower terms) and equivalence (e.g. synonyms) relationships between terms. It also discusses how terms are organized in a thesaurus and criteria for evaluating the effectiveness of a thesaurus.

1. A. ROSELINE
MLIS 2ND YEAR
PONDICHERRY UNIVERSITY

2. The word `thesaurus' comes from Greek
term `thesauros' meaning a storehouse or
treasury of words.
Quotes its use in 1736 as a treasury or
store house of knowledge.
Thesaurus was first conceived by Peter
Mark Roget, who brought out in 1825 his
thesaurus of “English words and Phrases”.

3. A compilation of words and phrases
showing synonyms and hierarchical and
other relationships and dependencies, the
function of which is to provide a
standardized vocabulary for information
storage and retrieval systems.
(Rowely,1992)
A thesaurus is a book of words that shows
relationship among the words it contains.
(Allen Kent)

4.  To provide standard vocabulary for a given subject
area by exercising control on the vocabulary of terms
used in an indexing language.
 To provide an aid to indexers in selecting term(s) for
describing the subject matter of documents.
 To help users to formulate their queries precisely.'
 To provide display of-relationships between terms to
facilitate the conduct of a comprehensive search
systematically.
 To provide a system of references between terms
which will ensure that only one term from a set of
synonyms is to be used both for indexing and
searching.

5. 1. Descriptors
2. Non descriptors
3. Relationship between terms
i. Hierarchical relationship
ii. Non-Hierarchical relationship

6. „ The terms that have been defined for use
by the thesaurus.
For use in indexes.
Descriptor should be nouns, either single
nouns, noun phrases or nouns with
qualifiers indicated in parentheses

7. Motor vehicles
MT 6.60 Equipment and facilities
UF Automobiles
UF Cars
UF Trucks
BT Vehicles
RT Road Engineering
RT Road Transport

8.  Š A non-descriptor, also called forbidden
term, is a term designating a concept very
close to that represented by a descriptor.
 Š It contains a reference to the
corresponding descriptor as the only
relationship

9. Non-descriptor
Automobiles
USE Motor vehicles
Cars
USE Motor vehicles
Trucks
USE Motor vehicles

10. It shows the interrelationship between
concepts in a hierarchy.
 It refers to super ordinate and subordinate
relationship for a concept.
 This relationship may be of three types:
i. Genus-Species (Generic)
relationship
ii. Hierarchical Whole-Part relationship
iii. Instance Relationship

11. It links genus and species and represents
the basis of scientific, taxonomic system.
For Example:
Capital Markets
BT Financial Markets
Financial Markets
NT Capital Markets

12. It means that the name of a part implies
the name of its whole in any context.
For Example:
Science
NT Physical Chemistry
Physical Chemistry
BT Science

13. occurs in a particular instance, which links
proper name with common noun.
For Example:
Mountain
NT Himalayas
Himalayas
BT Mountain Regions

14. Two terms are related other than
hierarchical, the relationship may be called
non-hierarchical relationship. Two types are:
i. Equivalence (or preferential) relationship
ii. Associative (or affinitive) relationship

15.  It refers to the preferred terms and
distinguishes such terms from the non-
preferred terms.
 When terms are regarded as similar or almost
the same in meaning, they can be combined
with the same concept. Synonyms, near-
synonyms, and quasi-synonyms come under
this category.
 The symbols used to represent these
relationships in a thesaurus are USE and OF
(Used For).

16. For Examples:
1. Popular names and scientific names
E.g. Onion/ Allium cepa
2. Variant spelling
E.g. Pray/ Prey
3. Terms from different cultures
E.g. Flat/ apartment
4. Abbreviations and full names
E.g. WHO/ World Health Organization

17.  This relationship is employed to cover other
relationship between terms that are related
but are neither consistently hierarchical nor
equivalent. They are indicated by the code RT
(Related Terms).
 Two types of associative relationship are:
i. Same Category e.g. Aero plane -
Helicopter
ii. Different category
e.g. Operating system - Software

18.  DESCRIPTOR
(With scope note whenever needed)
 Synonyms and quasi-synonyms
(displaying equivalence relationship and denoted by the relationship
indicator USE/UF (Use For)
 Broader Terms
(displaying hierarchical - subordinate relationship and denoted by
BT)
 Narrower Terms
(displaying hierarchical - subordinates relationship and denoted by
NT)
 Related Terms
(displaying associate relationship and denoted by RT)
 Top Term
(displaying hierarchical - subordinates relationship and denoted by
TT . Top term or TT is not repeated when all the descriptors belong to
the same broad class).

19. 1. Need Analysis:
The thesaurus need analysis should be done
first, whether it is really needed or not. There may be
existing thesaurus on similar subjects.
2. Gathering of Terms:
The terms are collected using two principles -
Principle of Literary warrant and Principle of User
Warrant. In the former the logic is that a term justifies
its inclusion if it is used in literature of the subject.
The method is to go through abstracting sources,
reference sources, periodical articles, etc. In the later
case, users/ subject specialists may be consulted to
gather the terms.

20. 3. Organization of Terms
To be organized into major categories and
into hierarchies within the categories. Useful
inter-hierarchical relationships should also be
delineated.
4. Organization into Hierarchies
Once the categories are identified, the next
stage is to organize each term into hierarchies.
Indexing Languages –Part I: Concepts and
Types, Subject Headings Lists and Thesauri

21. 5. Creation of Alphabetical Thesaurus
The hierarchies are established, the
classification is inserted to create alphabetical
thesaurus.
Each term becomes an entry and its
hierarchical relationships are denoted by BT
and NT. All the BT and NT terms should
reciprocate.
Similarly the non-hierarchical relationships
are shown through use, used for and related
terms (RTs).

22. 6. Presentation of Thesaurus
Each block of entries are arranged according to
requirement. It may be alphabetical, systematic (to
complement) or graphic.
7. Admission and deletion of terms
The job of inclusion of terms along with all their
relationships into the thesaurus, and their display in
the chosen format. At this stage some terms may
need to be added or deleted.
8. Evaluation
Once the thesaurus is compiled it needs to be
evaluated to assess its retrieval effectiveness.

23. 9. Review
Once the thesaurus has been compiled, it
has to be reviewed by subject experts and
modified as necessary
10. Maintenance
a thesaurus is developed, it should be
maintained properly. New terms need to
be added or deleted as the case may be.
This has to be done continuously.

24. 1. Alphabetical display:
In this form of display all indexing
terms, whether preferred or non-
preferred, are organized in a alphabetical
sequence. Each preferred term in the
following order:
i. Scope note or definition
ii. UF references to non-preferred
equivalent terms

25. iii. TT references to top-terms
iv. BT references to broader terms
v. NT references to narrower terms
vi. RT references to related terms.
Non-preferred terms are accompanied only by references
(e.g. USE) to the preferred terms.
PREFERRED TERM
SN Scope note
UF Use for
BT Broader term
NT Narrower term
RT Related term
Non-preferred term
Use PREFERRED TERM

26. MICROFORMS
SN A miniature of replica of document
UF Micro copies
BT Data media
NT Micro transparencies Micro-opaques
RT Microphotography

27. 1. Categories or hierarchies of terms
arranged according to their meanings and
logical relationships, and
2. An alphabetical index that directs the
user to the appropriate part of the
systematic section.

28. Graphic display shows the indexing
terms and their relationship in the
form of two dimensional figures,
which are supplemented by
alphabetical sections. There are
two types
1. Tree Structures and
2. Arrowgraphs

29.  NAL Agriculture Thesaurus (United States National Agricultural
Library, United States Department of Agriculture)
 Evaluation Thesaurus (By M. scriven)
 Thesaurus of Psychological index Terms CAPA
 Clinicians’ Thesaurus (By E. Zukerman)
 ROGET'S Thesaurus
(http://humanities.uchicago.edu/forms_unrest /ROGET.html)
 Thesaurus of Engineering and Scientific Terms (TEST)
 ERIC Thesaurus for Education
 Thesaurus of American Psychological Association (APA)
 UNESCO Thesaurus, etc.

30. Davis and Rush propose the following criteria for
evaluating thesaurus.
 Terminology: is it appropriate for the field, up-to-date
and accurate?
 Scope: is it too broad or too narrow to cover the field
adequately?
 Subdivisions: are there reasonable subdivisions?
 Definitions and notes: are enough included for clarity?
 References: are they adequate in both number and
form?
 Format: is it legible?
 Classification numbers: is the listing keyed to any kind
of classification scheme, if appropriate?

31. 1. To provide a map of a given field of
knowledge, which helps an indexer or a searcher to
understand the structure of the field.
2. To provide a standard vocabulary for a given
subject field.
3. To provide a system of references between terms
which will ensure that only one term from a set of
synonyms is used for indexing one concept.
4. To provide a guide for users of the systems so that
they choose the correct term for a subject search.
5. The use of terms in a given subject field may be
standardized.

32.  Thesauri is a vocabulary control in an indexing
language.
 It is a list of terms arranged in some meaningful
form and provides hierarchically and non-
hierarchically.
 It provides control over synonyms, it distinguishes
homographs and it brings related terms.
 Exert terminology control in choosing proper
headings subject cataloguing and indexing.
 Increases speed of information retrieval system.
 It helps for the user find out information on a
specific topic but also on related topics.