Some new fixed point theorems are presented for operators of accretive, nonlinear contractive, or nonexpansive type. These results are then used to establish a new existence principle for second order boundary value problems in Hilbert spaces.
A fixed point theorem for o-minimal structures
β Scribed by Kam-Chau Wong
- Publisher
- John Wiley and Sons
- Year
- 2003
- Tongue
- English
- Weight
- 113 KB
- Volume
- 49
- Category
- Article
- ISSN
- 0044-3050
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β¦ Synopsis
Abstract
We prove a definable analogue to Brouwer's Fixed Point Theorem for oβminimal structures of real closed field expansions: A continuous definable function mapping from the unit simplex into itself admits a fixed point, even though the underlying space is not necessarily topologically complete. Our proof is direct and elementary; it uses a triangulation technique for oβminimal functions, with an application of Sperner's Lemma. (Β© 2003 WILEYβVCH Verlag GmbH & Co. KGaA, Weinheim)
π SIMILAR VOLUMES
Let D be a closed nonempty subset of a Banach space X and T : D Βͺ X Γ 4 2 \_ a multivalued contraction with closed values, i.e., each Tx is a nonempty closed subset of X and there exists 0 F k -1 such that 5 5 H Tx, Ty F k x y y , x, y g D, ## Ε½ . where H denotes the Hausdorff metric H A, B s ma
The following theorem generalizes results given by FISHER [l] and Jungck [3].
In this paper we focus on three fixed point theorems and an integral equation. Schaefer's fixed point theorem will yield a Tperiodic solution of z(t) = a(t) + D(t, s)g(s, z(s)) ds 6, if D and g satisfy certain sign conditions independent of their magnitude. A combination of the contraction mapping t