LIS618 lecture 3

Thomas Krichel

2002-09-23

Structure of talk

• The blue sheet• Working with Dialog• Nexis.com

using dialog

• go to command search

• pass warning screen

• you get to "dialog web command search"

• http://www.dialogweb.com/cgi/logoff?mode=guided&url=/cgi/dwframe?href=search.html

• searches there do not work well at this level

blue sheet

• each database name is linked to a blueish pop-up window called the blue sheet for the database

• Contents of bluesheet is covered later• at this stage we choose a database and hit

"begin". We see that there is a command selected: "be numbers" where numbers are the ones for the databases selected, separated by comma.

database types

• full-text database

• bibliographic databases

• directory databases

• numeric databases– but they are not classified as such

finding a database

• file 411 contains the database of databases

• 'sf category' selects files belonging to a category category

• categories are listed at http://library.dialog.com/bluesheets

• 'b ref,ref' will select databases

closer look at the bluesheet

• file description• subject coverage (free vocabulary)• format options, lists all formats

– by number (internal)– by dialog web format (external, i.e. cross-

database)

• search options– basic index, i.e. subject contents– additional index, i.e. non-subject

search options: basic index

• select without qualifiers searches in all fields in the basic index

• bluesheet lists field indicators available for a database

• also note if field is indexed by word or phrase. proximity searching only works with word indices. when phrases are indexed you don't need proximity indicators

search in basic index

• basic index is queried through /IN, where IN is a field indicator

• Thomas calls this a appending indicator

• several field indicators can be ORed by giving a comma separated list, example

• mate/ti,de

additional features

• Some databases allow to restrict the search with unary expressions– /ABS require abstract present– /ENG English language publication

• Some fields are sortable with the sort command, i.e. records can be sorted by the values is the fields

Such d are database specific.

additional indices

• additional indices lists those terms that can lead a query. Often, these are phrase indexed.

• Such fields a queried by prefix IN=term where IN is the field abbreviator and term is the search term

• Thomas calls this a pre-pending indicator

the 's' (select) command

• Once issued the "be" command to select a database, we issue the "s" command:

• "s keywords" where keywords is a Boolean expression.

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

• probably just searches the main index

• keywords can be added

display

• you are allowed to select a format and a number of items to be displayed.

• formats vary from database to database, some databases can not display certain formats

Setting additional terms

• It appear that "drinking and mate" seems a better search term…

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

• prefix queries can be formed by appending a '?' to the query term.

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 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.

connectors III

• (F) words in the same field, no order

• (L) words in the same descriptor field, used to link headings and sub-headings. This is a hierarchical connector.

• Note: connectors are processed left-to-right. Use parenthesis whenever in doubt.

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)

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!

Reminder: fielded searches

• search terms can be limited to fields by appending '/field_identifier' to the query term, where field_identifier is the identifier of a field.

• identifiers of fields are also important in the "expand" command

common field identifiers

• 'co' company name• 'de' descriptor• 'au' author name • 'df' one-word descriptor• 'ti' title• 'cc' classification value• 'pn' product name• 'pc' product code• 'px' company type

narrowing by date

• 'PY=yyyy', where 'yyyy' is the four digit identifier for a year, limits the publication

• 'PD=yyyymmdd' where 'yyyy' is the four digit identifier for a year, when 'mm' is a two-digit identifier

expanding queries

• names have to be entered as they appear in the database.

• The "expand" command can be used to see varieties of spelling of a number.

• It has to be used in conjunction with a field identifier, example

expand au=cruz, b? to search for misspellings of José Manuel

Barrueco Cruz

expanding queries

• search produces results of the form

Ref Items Index-term– Ref is a reference number– Items is the number of items where the

index term appears– Index-term is the index term

• "s Ref" searches for the reference term.

DS (display sets)

• This command can be executed any time to review the sets that have been formed since the last B (begin) command.

the stop words

• an and by for from of the to with

add/repeat

• add number, number

adds databases by files to the last query

example add 297 to see what the bible says about it

• repeat

repeats previous query with database added

the target command

• "target set" where set is a search result fixes a subset of the "statistically most relevant results"

• new result set is being formed.