LCSH: Pre- vs. Post-Coordination

In 2007, Library of Congress released a report: Library of Congress Subject Headings: Pre- vs. Post-Coordination and Related Issues.

The report lists the pros and cons of the two different approaches. For those who are interested to know the comparison, the report is a ‘must read’.

In summary, the LC concluded that though the pre-coordinated system is still the best way to build a subject heading system for such a wide scale. The pre-coordinated system provides a best view of the context of subject matters of the work being described. To quoted an example cited in the Appendix II of the report:

‘The work “Evitas Geheimnis” has the following subject headings:

600 10 Peron, Eva, ‡d 1919-1952 ‡x Travel ‡z Switzerland.
600 10 Peron, Juan Domingo, ‡d 1895-1974.
651 _0 Argentina ‡x Ethnic relations.
650 _0 Voyages and travels.
651 _0 Argentina ‡x Foreign relations ‡z Switzerland.
651 _0 Switzerland ‡x Foreign relations ‡z Argentina.
650 _0 Immigrants ‡z Argentina ‡x History ‡y 20th century.
650 _0 Bank accounts ‡z Switzerland.
650 _0 Antisemitism ‡z Europe ‡x History.
651 _0 Argentina ‡x Emigration and immigration.
651 _0 Germany ‡x Emigration and immigration.
650 _0 War criminals ‡z Germany ‡x History ‡y 20th century.
650 _0 War criminals ‡z Argentina ‡x History ‡y 20th century.
650 _0 Nazis ‡z Argentina ‡x History.

After removing the duplicate headings, there are 20 separate concepts represented.

1895-1974
1919-1952
20th century
Antisemitism
Argentina
Bank accounts
Emigration and immigration
Ethnic relations
Europe
Foreign relations
Germany
History
Immigrants
Nazis
Peron, Eva
Peron, Juan Domingo
Switzerland
Travel
Voyages and travels
War criminals

This means there are 2,432,902,008,176,640,000 possible combinations of these terms. There are quite a few chances to get some false drops in this set of terms.’