Fixed Point Theory

Fixed point theorems in Nonlinear Analysis.

The approximation of the fixed points in Caristi theorem and the connection with Ekeland theorem were considered in

  • M.-C. Anisiu, On maximality principles related to Ekeland’s theorem, Seminar on Functional Analysis and Numerical Methods, 1-8, Preprint, 87-1, Univ. “Babeş-Bolyai” Cluj-Napoca, 1987.

In the book

a chapter is dedicated to fixed point theorems.

Convergence of the Mann and Ishikawa type iterations.

Results on the equivalence of the convergence of certain iterations have been obtained.

Local convergence of the successive approximations.

The high convergence orders of the successive approximations were characterized, an estimation of the attraction balls were obtained, and some results on the acceleration of the convergence of the successive approximations are given in:

Solutions of differential equations as fixed points.

In this direction we obtained existence, uniqueness results, data dependence and Ulam stability for the solution of functional-differential equations, differential equations with delays and mixed type argument.

  • D. Otrocol, I.A. Rus, Functional-differential equations with “maxima” via weakly Picard operators theory, Bull. Math. Soc. Sci. Math. Roumanie, 51(99) 2008, no. 3, 253-261.
  • D. Otrocol, I.A. Rus, Functional-differential equations with maxima of mixed type, Fixed Point Theory, 9 (2008) no. 1, 207-220.
  • D. Otrocol, V.A. Ilea, Ulam stability for a delay differential equation, Central European Journal of Mathematics, 11 (2013) no. 7, 1296-1303.

The convergence of the sequence of the successive approximation by using contraction principle and step method with a weaker Lipschitz condition and a new algorithm of successive approximation sequence generated by the step method were obtained in