LIS618 lecture 4 Thomas Krichel 2003-02-19. Structure of talk Before online searching Introduction to online searching Introduction to DIALOG –Overview.

LIS618 lecture 4

Thomas Krichel

2003-02-19

Structure of talk

• Before online searching • Introduction to online searching• Introduction to DIALOG

– Overview– bluesheets

before a search I

• what is purpose– brief overview– comprehensive search

• What perspective on the topic– scholarly– technical– business– popular

before search II

• What type of information– Fulltext– Bibliographic– Directory– Numeric

• Are there any known sources?– Authors– Journals– Papers– Conferences

before search III

• What are the language restrictions?

• What, if any, are the cost restrictions?

• How current need the data to be?

• How much of each record is required?

DIALOG

Literature

http://training.dialog.com/sem_info/courses/pdf_sem/dlg1.pdf

http://training.dialog.com/sem_info/courses/pdf_sem/dlg2.pdf

http://training.dialog.com/sem_info/courses/pdf_sem/dlg3.pdf

http://training.dialog.com/sem_info/courses/pdf_sem/dlg4.pdf

Dialog is a databank

• over 500 databases• these are also known as files and cover

– references and abstracts for published literature,

– business information and financial data;– complete text of articles and news stories;– statistical tables– Directories

• DIALOG uses the Boolean model

DIALOG interface

• is still rooted in "traditional" database systems

• dismissed as "dial-a-dog"

• is uses a command-driven interface

• it is very complicated to learn fully

• it is not suitable for the end-user

• it therefore offers a valuable skill to the information professional

• it is a challenge for a professor to teach

Accessing DIALOG

• On the web, go to

• http://www.dialogweb.com/

• Enter username and password, then click on logon

• When it is all done, click logoff in the top menu.

two steps in DIALOG

• step one: select databases (aka files) to look at

• step two: perform searches on the selected databases

• You may wonder why one does not have one single step like in a search engine. Discuss.

• today we concentrate on the second step

working on selected files

• We assume that we have selected database that we know and we look at the search interface on the selected database.

• The database selection process is a bit more complicated, covered next week.

• First, let us login and look at the command prompt.

• Then we select the first database (file) with the begin command

The begin command

• As its name suggests, usually the first command.

• begin number, number,…

• selects files with numbers number

• Once they are selected they can be searched.

• Now select the ERIC "begin 1"

• "Begin 1" can be abbreviated as "b 1"

Substeps in the second step

• Identify search terms

• Use Dialog basic commands to conduct a search

• View records online or print the results

the 's' (select) command

• Once issued the "begin" command to select a database, we issue the "s" command on the database.

• "s query_terms" where query_terms are the query terms

• This will search the index of selected database in full-text view for the query issued

• It will not find any of the following: "an and by for from of the to with". They are stop words.

connectors

• If you want to use several keywords there are three ways– you can truncate search terms – you can build an expression by putting

several keywords together. This is achieved by DIALOG's connectors.

– you can combine several expressions with the use of Boolean operators

• we will cover this is in turn now

truncation of terms

• Open Truncation– "select path?" retrieves all words that begin

with path: paths, pathos, pathway, pathology

• Controlled-Length Truncation– "select path? ?" retrieves the root and up to

one additional character: paths– "select path??" retrieves the root and up to

two additional characters: paths, pathos

truncation of terms II• Embedded Character truncation can be used

for variant spellings:– "select organi?ation" -> organization

organisation – "select fib??board" -> fiberboard fibreboard 

• This truncation feature is also useful for searching for unusual plural forms:– "select wom?n" -> woman women

• You can also do prefixes by putting the ? in the beginning. – "?mobile" -> automobile metamobile

Use of connectors

• Connectors are used to put several words together.

• One instance where this is useful is when you have words that on their own mean different things.

• For example "mate" is a herbal beverage consumed in South America. Looking for mate on the Internet retrieves a lot of singles' pages.

terms connected to mate

• What other terms to be used? – matear (suck mate)– matero (mate sucker)– cebar (prepare mate)– cebador (mate preparer) – yerba (mate herb)– bombilla (mate straw)

connectors I

• '(W)' requires terms to appear one after the other next to each other e.g. 'yerba(W)mate?' matches "yerba mate".

• '(i W)' where i is an integer, means followed by at most i words, e.g. 'ceba?(3W)mate?' matches "cebar un maravilloso mate" but not "cebador guapo mirando un buen mate"

connectors II

• '(N)' requires terms to be next to each other e.g. 'yerba(N)mate?' matches "yerba mate" or "mate yerba".

• '(i N)' where i is an integer, means proximity by at most i words, e.g. 'ceba?(3N)mate?' matches "cebar mate" or "matear con la cebadora".

• '(S)' searches for the occurrence of connected terms in the same paragraph.

using Boolean operators

• In your query, you can combine several expressions with Boolean operators

• Example: "?SELECT LIBRARY(W)SCHOOL? AND DISTANCE(W)EDUCATION"

• But I usually do not issue such fancy queries.

executing several searches

• there can be several searches done sequentially, and the results sets are saved by the system.

• Each time the system assigns a set number.

• These can be combined in Boolean expressions, e.g. 's S1 or S2 and S3'

• Remember that Boolean operations are set-theoretic!

Boolean operators

• when using Booleans, be aware that "and" has higher precedence than "or".

• Thus:a or b and c

is not the same as

(a or b) and c

but it is

a or (b and c)

type command

type set/format/range

• set is a result set

• format is a format

• range can be – start – end

• start is a record number to start• end is a record number to end

– all

formats are defined

• 2 -- full record except abstract• 3 or medium – citation• 5 or long – full except full text• 6 or free – title and dialog number• 8 or short – title plus indexing terms

– useful to find other indexing terms

• 9 or full – everything• KWIC or K – keywords in context

http://openlib.org/home/krichel

Thank you for your attention!