**2. Existing approaches for conflict resolution**

When navigation occurs in an environment that is totally or partially unknown or even dynamically changing, higher degree of autonomy for a mobile robot is required. Thus, a mobile robot should be able to take decisions on-line and to minimise conflict situations in such uncertain and dynamic environments using only sensors' limited information.

In this context, a wide range of approaches have been adopted to suggest solutions to the problem of space conflict when a robot shares the same environment with other actors.
