... visiting the research Institute of Mathematics, Seoul National University.Author details1Department of Mathematics, Hanyang University, Seoul 133-791, Republic of Korea2Department of Mathematics,University ... Mathematics,University of Ulsan, Ulsan 680-749, Republic of Korea3Department of Mathematics, Daejin University, Kyeonggi 487-711, Republic of Korea4Department of Mathematics, University of Seoul, Seoul ... Republic of KoreaAuthors’ contributionsAll authors conceived of the study, participated in its design and coordination, drafted the manuscript, participated in the sequence alignment, and read and...