All Questions
Tagged with metric-spaces fixed-point-theorems
9 questions
0
votes
0
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99
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Banach fixed point theorem / convergence squeeze
I am trying to prove a convergence result on an iterative scheme which has the initial point defined as
$$x_1 = \frac{1 - s(x_0)}{s(x_0)}$$
where s(x) is some unknown function.
Here is my theorem and ...
- 51
2
votes
0
answers
265
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The contraction principle in quasi metric spaces
I am researching contractive mappings and I need the article of I. A. Bakhtin "The contraction principle in quasi metric spaces"(1989) or at least part where explanation is given for ...
- 63.9k
3
votes
1
answer
148
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Is this sum of nonexpansive maps itself nonexpansive?
For Hilbert spaces $\mathcal{H}_X$, $\mathcal{H}_Y$ and $\mathcal{K}$, consider a linear map $f\colon \mathcal{K} \oplus \mathcal{H}_X \to \mathcal{K} \oplus \mathcal{H}_Y$ that is given as a matrix
$...
- 12.6k
2
votes
1
answer
177
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Takahashi minimization theorem for lower pseudo-continuous functions on complete metric spaces
Takahashi minimization theorem says : Let $(X,d)$ is a complete metric space, $f:X\to \mathbb{R}\cup\{+\infty\}$ is a proper(not constantly +$\infty$) lower semi continuous function, which is bounded ...
- 41.9k
1
vote
1
answer
454
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Base of topology for metric-like space
Let $X$ be a nonempty set and $p:X\times X\rightarrow\mathbb{R}^+ $ be a function satisfying the following conditions for all $x,y,z\in X$: \begin{align} &1)\enspace p(x,y)=0\implies x=y \\ &2)...
- 4,713
2
votes
0
answers
61
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Existence and uniqueness of fixed point in generalized condition of triangular norm
Definition 1) A Menger space is defined as a triple $\left( S,F,T \right)$ where $S$ is a set , $F$ is a collection of distribution functions and $T$ is a triangular norm function
$T:[ 0,1 ]\...
- 356
16
votes
5
answers
5k
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Converse to Banach's fixed point theorem?
Let $(X,d)$ be a metric space. Banach's fixed point theorem states that if $X$ is complete, then every contraction map $f:X\to X$ has a unique fixed point. A contraction map is a continuous map for ...
- 4,713
5
votes
1
answer
148
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Continuity of central point operation
Stanisław Mazur and Stanisław Ulam, in their joint paper, characterized the mid-point $\ \frac{a+b}2\ $ in a Banach space in pure metric terms (without algebra). This allowed them to show that any two ...
- 7,500
12
votes
1
answer
898
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Converse to Banach’s fixed point theorem for ordered fields?
Suppose $R$ is an ordered field. Call a continuous map $f: R \rightarrow R$ a contraction if there exists $r < 1$ (in $R$) such that $|f(x)-f(y)| \leq r |x-y|$ for all $x,y \in R$ (where $|x| := \...
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