Is there any safe way to change to chapter style for specific chapters?
This seems to be quite common, as, for instance, unnumbered chapters such as acknowledgements and other bureaucracies for a thesis in the form of chapters will look extremely weird for some chapter styles.
In my case, I'm using the book and the extbook class. Furthermore, I'm only intending to apply the non regular style to all the chapters after the third one. Also I need to change the enumeration from arabic to roman starting from the second chapter.
By chapter style I mean something like http://zoonek.free.fr/LaTeX/LaTeX_samples_chapter/0.html (if a concrete example is need, say the last one), including possibly the usage of the package titlesec.
I'm actually expecting that there's a general answer. In the negative case, I can specify further details if requested to do so.
Thanks in advance.