LIS618 lecture 3

1. LIS618 lecture 3 Thomas Krichel 2002-09-23

2. Structure of talk • The blue sheet • Working with Dialog • Nexis.com

3. 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

4. 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.

5. database types • full-text database • bibliographic databases • directory databases • numeric databases • but they are not classified as such

6. 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

7. 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

8. 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

9. 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

10. 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.

11. 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

12. 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

13. 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

14. 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.

15. 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"

16. 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.

17. 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.

18. 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)

19. 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!

20. 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

21. 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

22. 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

23. 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

24. 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.

25. 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

26. 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

27. 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.