# Nonlinear contractive conditions: A comparison and related problems

Jacek Jachymski; Izabela Jóźwik

Banach Center Publications (2007)

- Volume: 77, Issue: 1, page 123-146
- ISSN: 0137-6934

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topJacek Jachymski, and Izabela Jóźwik. "Nonlinear contractive conditions: A comparison and related problems." Banach Center Publications 77.1 (2007): 123-146. <http://eudml.org/doc/281677>.

@article{JacekJachymski2007,

abstract = {We establish five theorems giving lists of nonlinear contractive conditions which turn out to be mutually equivalent. We derive them from some general lemmas concerning subsets of the plane which may be applied both in the single- or set-valued case as well as for a family of mappings. A separation theorem for concave functions is proved as an auxiliary result. Also, we discuss briefly the following problems for several classes of contractions: stability of procedure of successive approximations, existence of approximate fixed points, continuous dependence of fixed points on parameters, existence of invariant sets for iterated function systems. Moreover, James Dugundji's contribution to the metric fixed point theory is presented. Using his notion of contractions, we also establish an extension of a domain invariance theorem for contractive fields.},

author = {Jacek Jachymski, Izabela Jóźwik},

journal = {Banach Center Publications},

keywords = {nonlinear contractive conditions; -contractive map; contractive fixed point; approximate fixed point; domain invariance theorem; separation theorem; semi-continuous function; monotonic function; concave function; subadditive function},

language = {eng},

number = {1},

pages = {123-146},

title = {Nonlinear contractive conditions: A comparison and related problems},

url = {http://eudml.org/doc/281677},

volume = {77},

year = {2007},

}

TY - JOUR

AU - Jacek Jachymski

AU - Izabela Jóźwik

TI - Nonlinear contractive conditions: A comparison and related problems

JO - Banach Center Publications

PY - 2007

VL - 77

IS - 1

SP - 123

EP - 146

AB - We establish five theorems giving lists of nonlinear contractive conditions which turn out to be mutually equivalent. We derive them from some general lemmas concerning subsets of the plane which may be applied both in the single- or set-valued case as well as for a family of mappings. A separation theorem for concave functions is proved as an auxiliary result. Also, we discuss briefly the following problems for several classes of contractions: stability of procedure of successive approximations, existence of approximate fixed points, continuous dependence of fixed points on parameters, existence of invariant sets for iterated function systems. Moreover, James Dugundji's contribution to the metric fixed point theory is presented. Using his notion of contractions, we also establish an extension of a domain invariance theorem for contractive fields.

LA - eng

KW - nonlinear contractive conditions; -contractive map; contractive fixed point; approximate fixed point; domain invariance theorem; separation theorem; semi-continuous function; monotonic function; concave function; subadditive function

UR - http://eudml.org/doc/281677

ER -

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