<p>We introduce the concept of <i>d</i>-Young distance function with respect to the 5-uplet <InlineEquation ID="IEq1"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="10_2024_1144_Article_IEq1.gif" Format="GIF" Height="19" Rendition="HTML" Resolution="72" Type="Linedraw" Width="87" /> </InlineMediaObject> <EquationSource Format="TEX">\((p,q,\tau ,\kappa ,\xi )\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mo stretchy="false">(</mo> <mi>p</mi> <mo>,</mo> <mi>q</mi> <mo>,</mo> <mi>τ</mi> <mo>,</mo> <mi>κ</mi> <mo>,</mo> <mi>ξ</mi> <mo stretchy="false">)</mo> </mrow> </math></EquationSource> </InlineEquation>, where <i>d</i> is a metric on a certain set <InlineEquation ID="IEq2"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="10_2024_1144_Article_IEq2.gif" Format="GIF" Height="14" Rendition="HTML" Resolution="72" Type="Linedraw" Width="13" /> </InlineMediaObject> <EquationSource Format="TEX">\(\Lambda \)</EquationSource> <EquationSource Format="MATHML"><math> <mi mathvariant="normal">Λ</mi> </math></EquationSource> </InlineEquation>, <InlineEquation ID="IEq3"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="10_2024_1144_Article_IEq3.gif" Format="GIF" Height="16" Rendition="HTML" Resolution="72" Type="Linedraw" Width="98" /> </InlineMediaObject> <EquationSource Format="TEX">\(1&lt;p,q&lt;\infty \)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mn>1</mn> <mo>&lt;</mo> <mi>p</mi> <mo>,</mo> <mi>q</mi> <mo>&lt;</mo> <mi>∞</mi> </mrow> </math></EquationSource> </InlineEquation> with <InlineEquation ID="IEq4"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="10_2024_1144_Article_IEq4.gif" Format="GIF" Height="25" Rendition="HTML" Resolution="72" Type="Linedraw" Width="68" /> </InlineMediaObject> <EquationSource Format="TEX">\(\frac{1}{p}+\frac{1}{q}=1\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mfrac> <mn>1</mn> <mi>p</mi> </mfrac> <mo>+</mo> <mfrac> <mn>1</mn> <mi>q</mi> </mfrac> <mo>=</mo> <mn>1</mn> </mrow> </math></EquationSource> </InlineEquation>, <InlineEquation ID="IEq5"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="10_2024_1144_Article_IEq5.gif" Format="GIF" Height="19" Rendition="HTML" Resolution="72" Type="Linedraw" Width="138" /> </InlineMediaObject> <EquationSource Format="TEX">\(\tau : \Lambda \times \Lambda \rightarrow [0,\infty )\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>τ</mi> <mo>:</mo> <mi mathvariant="normal">Λ</mi> <mo>×</mo> <mi mathvariant="normal">Λ</mi> <mo stretchy="false">→</mo> <mo stretchy="false">[</mo> <mn>0</mn> <mo>,</mo> <mi>∞</mi> <mo stretchy="false">)</mo> </mrow> </math></EquationSource> </InlineEquation>, <InlineEquation ID="IEq6"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="10_2024_1144_Article_IEq6.gif" Format="GIF" Height="13" Rendition="HTML" Resolution="72" Type="Linedraw" Width="42" /> </InlineMediaObject> <EquationSource Format="TEX">\(\kappa &gt;0\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>κ</mi> <mo>&gt;</mo> <mn>0</mn> </mrow> </math></EquationSource> </InlineEquation>, and <InlineEquation ID="IEq7"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="10_2024_1144_Article_IEq7.gif" Format="GIF" Height="19" Rendition="HTML" Resolution="72" Type="Linedraw" Width="138" /> </InlineMediaObject> <EquationSource Format="TEX">\(\xi : [0,\infty )\rightarrow [0,\infty )\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>ξ</mi> <mo>:</mo> <mo stretchy="false">[</mo> <mn>0</mn> <mo>,</mo> <mi>∞</mi> <mo stretchy="false">)</mo> <mo stretchy="false">→</mo> <mo stretchy="false">[</mo> <mn>0</mn> <mo>,</mo> <mi>∞</mi> <mo stretchy="false">)</mo> </mrow> </math></EquationSource> </InlineEquation> satisfies the condition <InlineEquation ID="IEq8"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="10_2024_1144_Article_IEq8.gif" Format="GIF" Height="25" Rendition="HTML" Resolution="72" Type="Linedraw" Width="95" /> </InlineMediaObject> <EquationSource Format="TEX">\(\inf _{t&gt;0} \frac{\xi (t)}{t^\kappa }&gt;0\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <msub> <mo movablelimits="true">inf</mo> <mrow> <mi>t</mi> <mo>&gt;</mo> <mn>0</mn> </mrow> </msub> <mfrac> <mrow> <mi>ξ</mi> <mo stretchy="false">(</mo> <mi>t</mi> <mo stretchy="false">)</mo> </mrow> <msup> <mi>t</mi> <mi>κ</mi> </msup> </mfrac> <mo>&gt;</mo> <mn>0</mn> </mrow> </math></EquationSource> </InlineEquation>. We establish some properties of the introduced distance function. Next, we study the existence and uniqueness of fixed points for some classes of mappings <InlineEquation ID="IEq9"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="10_2024_1144_Article_IEq9.gif" Format="GIF" Height="14" Rendition="HTML" Resolution="72" Type="Linedraw" Width="78" /> </InlineMediaObject> <EquationSource Format="TEX">\(F: \Lambda \rightarrow \Lambda \)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>F</mi> <mo>:</mo> <mi mathvariant="normal">Λ</mi> <mo stretchy="false">→</mo> <mi mathvariant="normal">Λ</mi> </mrow> </math></EquationSource> </InlineEquation> satisfying contractions involving the <i>d</i>-Young distance function. In particular, for a special choice of the 5-uplet <InlineEquation ID="IEq10"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="10_2024_1144_Article_IEq1.gif" Format="GIF" Height="19" Rendition="HTML" Resolution="72" Type="Linedraw" Width="87" /> </InlineMediaObject> <EquationSource Format="TEX">\((p,q,\tau ,\kappa ,\xi )\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mo stretchy="false">(</mo> <mi>p</mi> <mo>,</mo> <mi>q</mi> <mo>,</mo> <mi>τ</mi> <mo>,</mo> <mi>κ</mi> <mo>,</mo> <mi>ξ</mi> <mo stretchy="false">)</mo> </mrow> </math></EquationSource> </InlineEquation>, we recover the Banach fixed point theorem. We also provide an example, where our approach can be used, but the Banach fixed point theorem is inapplicable.</p>

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d-Young distance function and existence of fixed points in complete metric spaces

  • Vladimir Rakočević,
  • Bessem Samet

摘要

We introduce the concept of d-Young distance function with respect to the 5-uplet \((p,q,\tau ,\kappa ,\xi )\) ( p , q , τ , κ , ξ ) , where d is a metric on a certain set \(\Lambda \) Λ , \(1<p,q<\infty \) 1 < p , q < with \(\frac{1}{p}+\frac{1}{q}=1\) 1 p + 1 q = 1 , \(\tau : \Lambda \times \Lambda \rightarrow [0,\infty )\) τ : Λ × Λ [ 0 , ) , \(\kappa >0\) κ > 0 , and \(\xi : [0,\infty )\rightarrow [0,\infty )\) ξ : [ 0 , ) [ 0 , ) satisfies the condition \(\inf _{t>0} \frac{\xi (t)}{t^\kappa }>0\) inf t > 0 ξ ( t ) t κ > 0 . We establish some properties of the introduced distance function. Next, we study the existence and uniqueness of fixed points for some classes of mappings \(F: \Lambda \rightarrow \Lambda \) F : Λ Λ satisfying contractions involving the d-Young distance function. In particular, for a special choice of the 5-uplet \((p,q,\tau ,\kappa ,\xi )\) ( p , q , τ , κ , ξ ) , we recover the Banach fixed point theorem. We also provide an example, where our approach can be used, but the Banach fixed point theorem is inapplicable.