Question about Olivier's method

Hello, I'm looking for information about Olivier's method in order to supplement a talk. I spent a lot of time on engine searchers and I didn't find something documented enough to make me understand the way of working of such a method. Then I decided to contact you directly. Because I use the php similar_text function using this method to study how regular sentences change when they spread in a sample of people. I thought you could help me. Do you know a webpage or something else where I could find information about Olivier's method ? Thank you very much, Best regards, AZMODAI Paul,