Belaidi, Benharrat; El Farissi, Abdallah; Latreuch, Zinelaâbidine
(JIPAM, 2009)
In this paper, we give a complete answer to Problem 1 and a partial answer to Problem 2 posed by F. Qi in [2] and we propose an open problem.
Acknowledgements: The authors would like to thank the referees for their helpful ...