Can someone help me with the questions from the article linkbelow?

http://ai.stanford.edu/~ang/papers/icraoss09-ROS.pdf

1. What is the problem?
2. Why is the problem important?
3. Are there other solutions?
4. How is the problem solved?
5. Does the solution always work?
6. Are there any possible improvements?

Asked Jan. 25, 2017