natural language recognition

[eluser]ebot[/eluser]
working on a project, i want to implement a function that will scan through a text or article and then tag it into its various category. lets say fetch an article submitted by a user, the function is such that it should scan through and know if the article just submitted is a scientific, political, new, blog, technology etc.. article and then tag it.
i dont know if Code igniter has some kind of library or class that does this.
i will be grateful if any knows if Code igniter has got this.

Thanks
EbotT