What is the paper "Oliver [1993]" describing a PHP algorithm to calculate text similarity?

There is a function similar_text() in the PHP library. The documentation (http://php.net/manual/en/function.similar-text.php) tells me that "This calculates the similarity between two strings as described in Oliver [1993]."

Despite extensive searching, I can't find the paper that "Oliver [1993]" is referring to; nor any candidate for who "Oliver" might be. The PHP source is undocumented. The only other refe开发者_开发百科rence to Oliver 1993 is in a forum at http://www.codeguru.com/forum/showthread.php?t=41089, and I think that information is derived from the PHP documentation.

Anyone aware of what this might be?

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Or this?

Programming Classics: Implementing the World's Best Algorithms (Hardback)
By (author) Ian Oliver

Publisher: Pearson Education
Published: 01 April 1994
ISBN 13: 9780131004139
ISBN 10: 013100413

http://www.bookdepository.co.uk/book/9780131004139/Programming-Classics

yes this should be it...

http://books.google.hu/books?id=e7D-mITABmEC&pg=PT501&lpg=PT501&dq=%22ian+oliver%22+%22programming+classics%22+similar_text&source=bl&ots=oavkzNrqVv&sig=1SY1by3i68vvjwo3J-suMv29Af0&hl=hu&ei=jGMfTPKUGN-XOMbWrfsL&sa=X&oi=book_result&ct=result&resnum=1&ved=0CBUQ6AEwAA#v=onepage&q=%22ian%20oliver%22%20%22programming%20classics%22%20similar_text&f=false

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UPDATED:

http://marc.info/?l=php-internals&m=124336339205964&w=2 suggests that the link is http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.52.1476

Decision Graphs - An Extension of Decision Trees (1993) by Jonathan J. Oliver 

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I'm thinking

Decision Graphs - An Extension of Decision Trees
Jonathan J. Oliver

Department of Computer Science
Monash University
Clayton, Victoria, Australia

http://www.mail-archive.com/internals@lists.php.net/msg42231.html, there is a link which gives you an old link to the document here: http://web.archive.org/web/19970527103907/http://www.cs.monash.edu.au/~jono/TechReports/TR173.dgraph.ps