Posted by: ses in LCSH, SKOS
TThere’s a critical difference between subject based knowledge organization schemes created to organize books and other documents, (e.g. LCC, DDC, and LCSH), which are defined in terms of the things which a work is about, and rigorous, class based ontologies that are based on the properties of the things themselves.
Some relationships may be valid in terms of subjects, but may not apply directly to the things themselves. For example, a car wheels are part of cars, and cars are a type of vehicle. These relationships are always* true, and are examples of two different types of hierarchical relationships – partitive (is-part-of) (BTP) , and generic (is-a-kind-of) (BTG)
Always-aboutness is the combination of all the different types of hierarchical relationship – this is the Broader Term (BT) relationship. In terms of aboutness, we can easily say that everything about car wheels is always about cars, and everything about cars is always about vehicles. We can also directly infer that everything about car wheels must always be about vehicles. In other words, the always-aboutness relationship must be transitive.
Transitivity doesn’t hold when you mix different types of hierarchy – car wheels are not a kind of vehicle, but that has nothing to do with the transitivity of plain unqualified Broader Term.
When thinking about systems for organizing information, it’s absolutely critical to remember the difference between the document, and the thing the document is about.
Or in other words:
2 Comments »
Posted by: ses in LCSH
This is the latest version of the Doorbell -> Mammal graph; it shows the direct and indirect broader terms of doorbells in LCSH.
This incarnation of the graphic adds one new piece of visual information that seems to be very very suggestive. Dashed lines are used to indicate broader term references that have never been validated since BT and NT references were automatically generated from the old SA (See Also) links in 1988. Click to download the PDF version

2 Comments »
Posted by: ses in LCSH
By a curious coincidence, I just noticed that the earliest surviving entries in the LCSH Subjects files were created on January 27th, 1986. This date would have been the first Monday after the ALA Midwinter conference (Jan 18th-22nd ,1986).
From the time stamps, it seems as if the system became live for new entries on this date. Older entries weren’t added until Feb 11th.
Less than half of these converted entries have had their references evaluated. This is suggestive.
Reference evaluation (008/29)
| Value |
Count |
Percentage |
| a (Evaluated) |
45,495 |
38% |
| b (Not Evaluated) |
46,387 |
39% |
| n (No References) |
27,320 |
23% |
| Total |
119,202 |
100% |
[LCSH 150s, established, as obtained from authorities.loc.gov of December 2006]
Simon
p.s.
The oldest surviving record, for “Grouper fisheries”, was assigned LCCN “sh 86000005″.
You should have seen the ones that got away.
No Comments »
Posted by: ses in LCSH
When you look at the Library of Congress Subject headings as individual entries it’s almost impossible to understand just how confused much of the hierarchical reference structure has become.
I’ve written some code to generate graphical representations for the Broader Terms of entries in the LCSH. The starting term appears at the bottom of the graph; according to the rules, this term is a specialization of every other term on the graph. Top level terms are highlighted using double circles.
Layout and rendering is courtesy of the wonderful graphviz (AT&T Research). I have generated dot files for all entries in the LCSH; I need to set up an dynamic renderer so they can be viewed online, but a p7zip archive raw dot is available here. (5M compressed, 672M uncompressed)
Lets see what the LCSH has to tell us about Doorbells.
Doorbells are a Social science. Doorbells are Souls. Doorbells are even Ontologies – which would explain why Protege keeps beeping at me. But most of all, Doorbells are mammals.
Obviously this conclusion is absurd. Everyone knows that doorbells aren’t hairy. But where are the errors that lead us to this mistaken conclusion, and how can we start to correct them? That’s the subject of tomorrow’s post.

3 Comments »