The concept and scope of usurpation in the Islamic law and Iran's civil law

In the sources of Islamic law, there are important and interesting discussions about concept and scope of usurpation. Some of these discussions have interned to civil code of Iran, but some of them has not codified in this code. With silence of code, we can use of these sources. For examples, if in the usurpation, possession on the property belonging to another person is sufficient or removal of possession of the owner is necessary too? Is the corpus of property is usurpable alone or the rights are usurpable also? Is the benefits of properties are usurpable as well as the corpus of property? Is the usurpation of joint property is possible by one of partners? In this article, the answers of these questions and the concept and scope of usurpation are studied.