Duplicate Content Filter Algorithm

[real_estate]

Hi,
Does anyone have a clue what is the approximate duplicate contect filter algorithm that google uses ?
How original - indexed content can be duplicated and in the same time be included in the google index?

[eyecandy]

No one knows this except some google engineers. However, you may want to look at their patents. It's not as simple as a percentage.

Here is Google's patent on duplicate content.

One way duplicate content is detected is by comparing the links on a page. This is a way AltaVista patented a while back.

Here is the AltaVista Patent