  Debugging is considered as a rigorous but important feature of software
engineering process. Since more than a decade, the software engineering
research community is exploring different techniques for removal of faults from
programs but it is quite difficult to overcome all the faults of software
programs. Thus, it is still remains as a real challenge for software debugging
and maintenance community. In this paper, we briefly introduced software
anomalies and faults classification and then explained different fault
localization models using theory of diagnosis. Furthermore, we compared and
contrasted between value based and dependencies based models in accordance with
different real misbehaviours and presented some insight information for the
debugging process. Moreover, we discussed the results of both models and
manifested the shortcomings as well as advantages of these models in terms of
debugging and maintenance.
