Department of Mathematics, Faculty of Science, King Mongkut's University of Technology Thonburi (KMUTT), Bangmod, Thrungkru, Bangkok 10140, Thailand
Copyright © 2011 W. Sintunavarat and P. Kumam. This is an open access article distributed under the
Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
The concept of tangential for single-valued
mappings is extended to multivalued mappings and used to prove
the existence of a common fixed point theorem of Gregus type for
four mappings satisfying a strict general contractive condition of
integral type. Consequently, several known fixed point results generalized
and improved the corresponding recent result of Pathak and
Shahzad (2009) and many authors.