LIS618 lecture 4 Thomas Krichel

Structure of talk Before online searching Introduction to online searching Introduction to DIALOG –Overview –bluesheets

before a searchI what is purpose –brief overview –comprehensive search What perspective on the topic –scholarly –technical –business –popular

before searchII What type of information –Fulltext –Bibliographic –Directory –Numeric Are there any known sources? –Authors –Journals –Papers –Conferences

before searchIII 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 pdf_sem/dlg1.pdf pdf_sem/dlg2.pdf pdf_sem/dlg3.pdf 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 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)

connectorsI '(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"

connectorsII '(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

Thank you for your attention!