<p>We prove that whenever <InlineEquation ID="IEq1"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="10_2024_1139_Article_IEq1.gif" Format="GIF" Height="20" Rendition="HTML" Resolution="72" Type="Linedraw" Width="153" /> </InlineMediaObject> <EquationSource Format="TEX">\(M_1,\dots ,M_n:I^k \rightarrow I\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <msub> <mi>M</mi> <mn>1</mn> </msub> <mo>,</mo> <mo>⋯</mo> <mo>,</mo> <msub> <mi>M</mi> <mi>n</mi> </msub> <mo>:</mo> <msup> <mi>I</mi> <mi>k</mi> </msup> <mo stretchy="false">→</mo> <mi>I</mi> </mrow> </math></EquationSource> </InlineEquation>, (<InlineEquation ID="IEq2"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="10_2024_1139_Article_IEq2.gif" Format="GIF" Height="17" Rendition="HTML" Resolution="72" Type="Linedraw" Width="61" /> </InlineMediaObject> <EquationSource Format="TEX">\(n,k \in \mathbb {N}\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>n</mi> <mo>,</mo> <mi>k</mi> <mo>∈</mo> <mi mathvariant="double-struck">N</mi> </mrow> </math></EquationSource> </InlineEquation>) are symmetric, continuous means on the interval <i>I</i> and <InlineEquation ID="IEq3"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="10_2024_1139_Article_IEq3.gif" Format="GIF" Height="20" Rendition="HTML" Resolution="72" Type="Linedraw" Width="144" /> </InlineMediaObject> <EquationSource Format="TEX">\(S_1,\dots ,S_m:I^k \rightarrow I\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <msub> <mi>S</mi> <mn>1</mn> </msub> <mo>,</mo> <mo>⋯</mo> <mo>,</mo> <msub> <mi>S</mi> <mi>m</mi> </msub> <mo>:</mo> <msup> <mi>I</mi> <mi>k</mi> </msup> <mo stretchy="false">→</mo> <mi>I</mi> </mrow> </math></EquationSource> </InlineEquation> (<InlineEquation ID="IEq4"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="10_2024_1139_Article_IEq4.gif" Format="GIF" Height="11" Rendition="HTML" Resolution="72" Type="Linedraw" Width="51" /> </InlineMediaObject> <EquationSource Format="TEX">\(m &lt; n\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>m</mi> <mo>&lt;</mo> <mi>n</mi> </mrow> </math></EquationSource> </InlineEquation>) satisfy a sort of embeddability assumptions then for every continuous function <InlineEquation ID="IEq5"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="10_2024_1139_Article_IEq5.gif" Format="GIF" Height="17" Rendition="HTML" Resolution="72" Type="Linedraw" Width="80" /> </InlineMediaObject> <EquationSource Format="TEX">\(\mu :I^n \rightarrow \mathbb {R}\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>μ</mi> <mo>:</mo> <msup> <mi>I</mi> <mi>n</mi> </msup> <mo stretchy="false">→</mo> <mi mathvariant="double-struck">R</mi> </mrow> </math></EquationSource> </InlineEquation> which is strictly monotone in each coordinate, the functional equation <Equation ID="Equ8"> <MediaObject> <ImageObject Color="BlackWhite" FileRef="10_2024_1139_Article_Equ8.gif" Format="GIF" Height="42" Rendition="HTML" Resolution="72" Type="Linedraw" Width="427" /> </MediaObject> <EquationSource Format="TEX">\( \mu (S_1(v),\dots ,S_m(v),\underbrace{F(v),\dots ,F(v)}_{(n-m)\text { times}})=\mu (M_1(v),\dots ,M_n(v)) \)</EquationSource> <EquationSource Format="MATHML"><math display="block"> <mrow> <mi>μ</mi> <mrow> <mo stretchy="false">(</mo> <msub> <mi>S</mi> <mn>1</mn> </msub> <mrow> <mo stretchy="false">(</mo> <mi>v</mi> <mo stretchy="false">)</mo> </mrow> <mo>,</mo> <mo>⋯</mo> <mo>,</mo> <msub> <mi>S</mi> <mi>m</mi> </msub> <mrow> <mo stretchy="false">(</mo> <mi>v</mi> <mo stretchy="false">)</mo> </mrow> <mo>,</mo> <munder> <munder accentunder="true"> <mrow> <mi>F</mi> <mo stretchy="false">(</mo> <mi>v</mi> <mo stretchy="false">)</mo> <mo>,</mo> <mo>⋯</mo> <mo>,</mo> <mi>F</mi> <mo stretchy="false">(</mo> <mi>v</mi> <mo stretchy="false">)</mo> </mrow> <mo>⏟</mo> </munder> <mrow> <mo stretchy="false">(</mo> <mi>n</mi> <mo>-</mo> <mi>m</mi> <mo stretchy="false">)</mo> <mspace width="0.333333em" /> <mtext>times</mtext> </mrow> </munder> <mo stretchy="false">)</mo> </mrow> <mo>=</mo> <mi>μ</mi> <mrow> <mo stretchy="false">(</mo> <msub> <mi>M</mi> <mn>1</mn> </msub> <mrow> <mo stretchy="false">(</mo> <mi>v</mi> <mo stretchy="false">)</mo> </mrow> <mo>,</mo> <mo>⋯</mo> <mo>,</mo> <msub> <mi>M</mi> <mi>n</mi> </msub> <mrow> <mo stretchy="false">(</mo> <mi>v</mi> <mo stretchy="false">)</mo> </mrow> <mo stretchy="false">)</mo> </mrow> </mrow> </math></EquationSource> </Equation>has the unique solution <InlineEquation ID="IEq6"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="10_2024_1139_Article_IEq6.gif" Format="GIF" Height="21" Rendition="HTML" Resolution="72" Type="Linedraw" Width="122" /> </InlineMediaObject> <EquationSource Format="TEX">\(F=F_\mu :I^k \rightarrow I\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>F</mi> <mo>=</mo> <msub> <mi>F</mi> <mi>μ</mi> </msub> <mo>:</mo> <msup> <mi>I</mi> <mi>k</mi> </msup> <mo stretchy="false">→</mo> <mi>I</mi> </mrow> </math></EquationSource> </InlineEquation> which is a mean. We deliver some sufficient conditions so that <InlineEquation ID="IEq7"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="10_2024_1139_Article_IEq7.gif" Format="GIF" Height="19" Rendition="HTML" Resolution="72" Type="Linedraw" Width="21" /> </InlineMediaObject> <EquationSource Format="TEX">\(F_\mu \)</EquationSource> <EquationSource Format="MATHML"><math> <msub> <mi>F</mi> <mi>μ</mi> </msub> </math></EquationSource> </InlineEquation> is well-defined (in particular uniquely determined) and study its properties. The aim of this research is to provide a broad overview of the family of Beta-type means introduced in (Himmel and Matkowski,&#xa0;2018).</p>

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Pexider invariance equation for embeddable mean-type mappings

  • Paweł Pasteczka

摘要

We prove that whenever \(M_1,\dots ,M_n:I^k \rightarrow I\) M 1 , , M n : I k I , ( \(n,k \in \mathbb {N}\) n , k N ) are symmetric, continuous means on the interval I and \(S_1,\dots ,S_m:I^k \rightarrow I\) S 1 , , S m : I k I ( \(m < n\) m < n ) satisfy a sort of embeddability assumptions then for every continuous function \(\mu :I^n \rightarrow \mathbb {R}\) μ : I n R which is strictly monotone in each coordinate, the functional equation \( \mu (S_1(v),\dots ,S_m(v),\underbrace{F(v),\dots ,F(v)}_{(n-m)\text { times}})=\mu (M_1(v),\dots ,M_n(v)) \) μ ( S 1 ( v ) , , S m ( v ) , F ( v ) , , F ( v ) ( n - m ) times ) = μ ( M 1 ( v ) , , M n ( v ) ) has the unique solution \(F=F_\mu :I^k \rightarrow I\) F = F μ : I k I which is a mean. We deliver some sufficient conditions so that \(F_\mu \) F μ is well-defined (in particular uniquely determined) and study its properties. The aim of this research is to provide a broad overview of the family of Beta-type means introduced in (Himmel and Matkowski, 2018).