similarity - Algorithm to find if one document is included in another, when those two documents are similar -

I am looking for an algorithm that finds that if two text documents are the same, where one document is in another document Includes.

Thank you in advance.

You can always use it, it is not accurate about the use of the FTP documentation algorithm (S) , But the original authors have written a letter about it ( Google for diff paper ), and you can always read the source code.

You will need a more accurate question for a more accurate answer. Are you only interested in knowing if a document is a piece of another document? Or are you interested in knowing if anyone can be divided into pieces in the same document in the same order? Or do you want to know how much content does not do if you try to match the contents of both documents with fast algorithms? The difference will tell you all those things or do you want to know the absolute best match? The difference does not always give you, you will need something. If one of the documents is much smaller than the other then you can use it fast etc. e.t.c.