Open Access Research

Fixed point theorems of ( a , b ) -monotone mappings in Hilbert spaces

Lai-Jiu Lin* and Sung-Yu Wang

Author Affiliations

Department of Mathematics, National Changhua University of Education, Changhua, 50058, Taiwan

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Fixed Point Theory and Applications 2012, 2012:131 doi:10.1186/1687-1812-2012-131

Published: 7 August 2012

Abstract

We propose a new class of nonlinear mappings, called <a onClick="popup('http://www.fixedpointtheoryandapplications.com/content/2012/1/131/mathml/M1','MathML',630,470);return false;" target="_blank" href="http://www.fixedpointtheoryandapplications.com/content/2012/1/131/mathml/M1">View MathML</a>-monotone mappings, and show that this class of nonlinear mappings contains nonspreading mappings, hybrid mappings, firmly nonexpansive mappings, and <a onClick="popup('http://www.fixedpointtheoryandapplications.com/content/2012/1/131/mathml/M3','MathML',630,470);return false;" target="_blank" href="http://www.fixedpointtheoryandapplications.com/content/2012/1/131/mathml/M3">View MathML</a>-generalized hybrid mappings with <a onClick="popup('http://www.fixedpointtheoryandapplications.com/content/2012/1/131/mathml/M4','MathML',630,470);return false;" target="_blank" href="http://www.fixedpointtheoryandapplications.com/content/2012/1/131/mathml/M4">View MathML</a>. We also give an example to show that a <a onClick="popup('http://www.fixedpointtheoryandapplications.com/content/2012/1/131/mathml/M1','MathML',630,470);return false;" target="_blank" href="http://www.fixedpointtheoryandapplications.com/content/2012/1/131/mathml/M1">View MathML</a>-monotone mapping is not necessary to be a quasi-nonexpansive mapping. We establish an existence theorem of fixed points and the demiclosed principle for the class of <a onClick="popup('http://www.fixedpointtheoryandapplications.com/content/2012/1/131/mathml/M1','MathML',630,470);return false;" target="_blank" href="http://www.fixedpointtheoryandapplications.com/content/2012/1/131/mathml/M1">View MathML</a>-monotone mappings. As a special case of our result, we give an existence theorem of fixed points for <a onClick="popup('http://www.fixedpointtheoryandapplications.com/content/2012/1/131/mathml/M3','MathML',630,470);return false;" target="_blank" href="http://www.fixedpointtheoryandapplications.com/content/2012/1/131/mathml/M3">View MathML</a>-generalized hybrid mappings with <a onClick="popup('http://www.fixedpointtheoryandapplications.com/content/2012/1/131/mathml/M4','MathML',630,470);return false;" target="_blank" href="http://www.fixedpointtheoryandapplications.com/content/2012/1/131/mathml/M4">View MathML</a>. We also consider Mann’s type weak convergence theorem and CQ type strong convergence theorem for <a onClick="popup('http://www.fixedpointtheoryandapplications.com/content/2012/1/131/mathml/M1','MathML',630,470);return false;" target="_blank" href="http://www.fixedpointtheoryandapplications.com/content/2012/1/131/mathml/M1">View MathML</a>-monotone mappings. We give an example of <a onClick="popup('http://www.fixedpointtheoryandapplications.com/content/2012/1/131/mathml/M1','MathML',630,470);return false;" target="_blank" href="http://www.fixedpointtheoryandapplications.com/content/2012/1/131/mathml/M1">View MathML</a>-monotone mappings which assures the Mann’s type weak convergence.

Keywords:
fixed point; demiclosed principle; strong convergence; weak convergence; nonspreading mapping; hybrid mapping; nonexpansive mapping; <a onClick="popup('http://www.fixedpointtheoryandapplications.com/content/2012/1/131/mathml/M1','MathML',630,470);return false;" target="_blank" href="http://www.fixedpointtheoryandapplications.com/content/2012/1/131/mathml/M1">View MathML</a>- monotone mapping; Mann’s type iteration; CQ type iteration