ACTA MATHEMATICA
UNIVERSITATIS COMENIANAE




Vol. LXXVII, 1 (2008)
p. 31 - 42

Convergence theorems for asymptotically nonexpansive mappings in Banach spaces

Yongfu Su, Xiaolong Qin and Meijuan Shang

Received: September 09, 2006;  Accepted: May 22, 2007



Abstract.  Let E be a uniformly convex Banach space, and let K be a nonempty convex closed subset which is also a nonexpansive retract of E. Let T: K ® E be an asymptotically nonexpansive mapping with {kn} Ì [1, ¥) such that (å from n=1 to ¥) (kn - 1) ¥ and let F(T) be nonempty, where F(T) denotes the fixed points set of T. Let {an}, {bn}, {gn}, {a¢n}, {b¢n}, {g¢n}, {a¢¢n}, {b¢¢n} and {g¢¢n} be real sequences in [0, 1] such that an + bn + gn = n + n + n = a¢¢n + b¢¢n + g¢¢n = 1 and e £ an, n, a¢¢n £ 1 - e for all n Î N and some e > 0, starting with arbitrary x1 Î K, define the sequence { xn} by setting
                                                       zn = P(a¢¢nT(PT)n-1xn + b¢¢nxn + g¢¢nwn),
                                                       yn = P(nT(PT)n-1zn + nxn + nvn),
                                                       xn+1 = P(anT(PT)n-1yn + bnxn + gnun),

with the restrictions (å from n=1 to ¥) (gn) ¥, (å from n=1 to ¥) (n) ¥ and (å from n=1 to ¥) (g¢¢n) ¥ where { wn} , { vn} and { un} are bounded sequences in K.
   (i)    If E is real uniformly convex Banach space satisfying Opial's condition, then weak convergence of { xn} to some p Î F(T) is obtained;
   (ii)    If T satisfies condition (A), then { xn} convergence strongly to some p Î F(T).

Keywords:  asymptotically nonexpansive; non-self map; composite iterative with errors; Kadec-Klee property; Uniformly convex Banach space.

AMS Subject classification: Primary:  47H09; 47H10; 47J25.


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