<p>The theory of the operator <Equation ID="Equ6"> <EquationSource Format="TEX">\(G(x) = |\underline{x}|^2 \frac{\partial }{\partial x_0} + \underline{x} \sum _{j=1}^n x_j \frac{\partial }{\partial x_j}\)</EquationSource> <EquationSource Format="MATHML"><math display="block"> <mrow> <mrow> <mi>G</mi> <mrow> <mo stretchy="false">(</mo> <mi>x</mi> <mo stretchy="false">)</mo> </mrow> <mo>=</mo> <mo stretchy="false">|</mo> </mrow> <munder> <mi>x</mi> <mo>̲</mo> </munder> <msup> <mrow> <mo stretchy="false">|</mo> </mrow> <mn>2</mn> </msup> <mfrac> <mi>∂</mi> <mrow> <mi>∂</mi> <msub> <mi>x</mi> <mn>0</mn> </msub> </mrow> </mfrac> <mo>+</mo> <munder> <mi>x</mi> <mo>̲</mo> </munder> <munderover> <mo>∑</mo> <mrow> <mi>j</mi> <mo>=</mo> <mn>1</mn> </mrow> <mi>n</mi> </munderover> <msub> <mi>x</mi> <mi>j</mi> </msub> <mfrac> <mi>∂</mi> <mrow> <mi>∂</mi> <msub> <mi>x</mi> <mi>j</mi> </msub> </mrow> </mfrac> </mrow> </math></EquationSource> </Equation>is deeply associated with the slice monogenic function theory and has grown in recent years. In particular, for <InlineEquation ID="IEq1"> <EquationSource Format="TEX">\(n=3\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>n</mi> <mo>=</mo> <mn>3</mn> </mrow> </math></EquationSource> </InlineEquation> the quaternionic version of <i>G</i> has been recently used to study the quaternionic slice regular function theory. This work extends the study of the <i>G</i> operator in two senses: a) Clifford’s analysis structure. The function theory induced by the operator <Equation ID="Equ7"> <EquationSource Format="TEX">\(\begin{aligned} {\mathcal {H}}_a (x) = {{\underline{a}}} ( {x}) \frac{\partial }{\partial x_0} - \sum _{i=1}^n \left( \sum _{j=1}^n a_j ( {x}) \frac{\partial (a^{-1})_i}{\partial y_j}\circ a ( {x}) \right) \frac{\partial }{\partial x_i}, \end{aligned}\)</EquationSource> <EquationSource Format="MATHML"><math display="block"> <mrow> <mtable> <mtr> <mtd columnalign="right"> <mrow> <msub> <mi mathvariant="script">H</mi> <mi>a</mi> </msub> <mrow> <mo stretchy="false">(</mo> <mi>x</mi> <mo stretchy="false">)</mo> </mrow> <mo>=</mo> <munder> <mi>a</mi> <mo>̲</mo> </munder> <mrow> <mo stretchy="false">(</mo> <mi>x</mi> <mo stretchy="false">)</mo> </mrow> <mfrac> <mi>∂</mi> <mrow> <mi>∂</mi> <msub> <mi>x</mi> <mn>0</mn> </msub> </mrow> </mfrac> <mo>-</mo> <munderover> <mo>∑</mo> <mrow> <mi>i</mi> <mo>=</mo> <mn>1</mn> </mrow> <mi>n</mi> </munderover> <mfenced close=")" open="("> <munderover> <mo>∑</mo> <mrow> <mi>j</mi> <mo>=</mo> <mn>1</mn> </mrow> <mi>n</mi> </munderover> <msub> <mi>a</mi> <mi>j</mi> </msub> <mrow> <mo stretchy="false">(</mo> <mi>x</mi> <mo stretchy="false">)</mo> </mrow> <mfrac> <mrow> <mi>∂</mi> <msub> <mrow> <mo stretchy="false">(</mo> <msup> <mi>a</mi> <mrow> <mo>-</mo> <mn>1</mn> </mrow> </msup> <mo stretchy="false">)</mo> </mrow> <mi>i</mi> </msub> </mrow> <mrow> <mi>∂</mi> <msub> <mi>y</mi> <mi>j</mi> </msub> </mrow> </mfrac> <mo>∘</mo> <mi>a</mi> <mrow> <mo stretchy="false">(</mo> <mi>x</mi> <mo stretchy="false">)</mo> </mrow> </mfenced> <mfrac> <mi>∂</mi> <mrow> <mi>∂</mi> <msub> <mi>x</mi> <mi>i</mi> </msub> </mrow> </mfrac> <mo>,</mo> </mrow> </mtd> </mtr> </mtable> </mrow> </math></EquationSource> </Equation>where <i>a</i> is a function with certain properties with domain in <InlineEquation ID="IEq2"> <EquationSource Format="TEX">\({\mathbb {R}}^{n+1}\)</EquationSource> <EquationSource Format="MATHML"><math> <msup> <mrow> <mi mathvariant="double-struck">R</mi> </mrow> <mrow> <mi>n</mi> <mo>+</mo> <mn>1</mn> </mrow> </msup> </math></EquationSource> </InlineEquation> is presented extending the already known results of the <i>G</i> (if <InlineEquation ID="IEq3"> <EquationSource Format="TEX">\(a=I\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>a</mi> <mo>=</mo> <mi>I</mi> </mrow> </math></EquationSource> </InlineEquation> is the identity function we can see that <InlineEquation ID="IEq4"> <EquationSource Format="TEX">\(G=-\underline{x}{\mathcal {H}}_I\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>G</mi> <mo>=</mo> <mo>-</mo> <munder> <mi>x</mi> <mo>̲</mo> </munder> <msub> <mi mathvariant="script">H</mi> <mi>I</mi> </msub> </mrow> </math></EquationSource> </InlineEquation>) such as Splitting Lemma, Representations Theorem, Cauchy formula, a characterization of the zero sets of <InlineEquation ID="IEq5"> <EquationSource Format="TEX">\({\mathcal {H}}_a\)</EquationSource> <EquationSource Format="MATHML"><math> <msub> <mi mathvariant="script">H</mi> <mi>a</mi> </msub> </math></EquationSource> </InlineEquation> and a power series development. Also, some properties of the material derivative: <Equation ID="Equ8"> <EquationSource Format="TEX">\(\begin{aligned} {D}_u = \frac{\partial }{\partial x_0} + \sum _{j=1}^n u_j \frac{\partial }{\partial x_j}, \end{aligned}\)</EquationSource> <EquationSource Format="MATHML"><math display="block"> <mrow> <mtable> <mtr> <mtd columnalign="right"> <mrow> <msub> <mi>D</mi> <mi>u</mi> </msub> <mo>=</mo> <mfrac> <mi>∂</mi> <mrow> <mi>∂</mi> <msub> <mi>x</mi> <mn>0</mn> </msub> </mrow> </mfrac> <mo>+</mo> <munderover> <mo>∑</mo> <mrow> <mi>j</mi> <mo>=</mo> <mn>1</mn> </mrow> <mi>n</mi> </munderover> <msub> <mi>u</mi> <mi>j</mi> </msub> <mfrac> <mi>∂</mi> <mrow> <mi>∂</mi> <msub> <mi>x</mi> <mi>j</mi> </msub> </mrow> </mfrac> <mo>,</mo> </mrow> </mtd> </mtr> </mtable> </mrow> </math></EquationSource> </Equation>where <i>u</i> is a certain <InlineEquation ID="IEq6"> <EquationSource Format="TEX">\({\mathbb {R}}^{n}\)</EquationSource> <EquationSource Format="MATHML"><math> <msup> <mrow> <mi mathvariant="double-struck">R</mi> </mrow> <mi>n</mi> </msup> </math></EquationSource> </InlineEquation>-valued function with domains in <InlineEquation ID="IEq7"> <EquationSource Format="TEX">\({\mathbb {R}}^{n}\)</EquationSource> <EquationSource Format="MATHML"><math> <msup> <mrow> <mi mathvariant="double-struck">R</mi> </mrow> <mi>n</mi> </msup> </math></EquationSource> </InlineEquation>, or <InlineEquation ID="IEq8"> <EquationSource Format="TEX">\({\mathbb {R}}^{n+1}\)</EquationSource> <EquationSource Format="MATHML"><math> <msup> <mrow> <mi mathvariant="double-struck">R</mi> </mrow> <mrow> <mi>n</mi> <mo>+</mo> <mn>1</mn> </mrow> </msup> </math></EquationSource> </InlineEquation>, are presented as consequences of function theory induced by <InlineEquation ID="IEq9"> <EquationSource Format="TEX">\({\mathcal {H}}_a\)</EquationSource> <EquationSource Format="MATHML"><math> <msub> <mi mathvariant="script">H</mi> <mi>a</mi> </msub> </math></EquationSource> </InlineEquation>. b) Structure of quaternionic analysis. In particular, the case <InlineEquation ID="IEq10"> <EquationSource Format="TEX">\(n=3\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>n</mi> <mo>=</mo> <mn>3</mn> </mrow> </math></EquationSource> </InlineEquation> is approached from the point of view of quaternionic analysis presenting results such as Splitting Lemma, Representations Theorem, Borel-Pompeiu, Stokes and Cauchy formulas, a conformal covariant property and a characterization of the zero sets of the quaternonic version of <InlineEquation ID="IEq11"> <EquationSource Format="TEX">\({\mathcal {H}}_a\)</EquationSource> <EquationSource Format="MATHML"><math> <msub> <mi mathvariant="script">H</mi> <mi>a</mi> </msub> </math></EquationSource> </InlineEquation> and its consequences for <InlineEquation ID="IEq12"> <EquationSource Format="TEX">\(D_u\)</EquationSource> <EquationSource Format="MATHML"><math> <msub> <mi>D</mi> <mi>u</mi> </msub> </math></EquationSource> </InlineEquation>.</p>

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Some Global Operators and the Material Derivative

  • J. O. González-Cervantes,
  • D. González-Campos,
  • Juan Bory-Reyes

摘要

The theory of the operator \(G(x) = |\underline{x}|^2 \frac{\partial }{\partial x_0} + \underline{x} \sum _{j=1}^n x_j \frac{\partial }{\partial x_j}\) G ( x ) = | x ̲ | 2 x 0 + x ̲ j = 1 n x j x j is deeply associated with the slice monogenic function theory and has grown in recent years. In particular, for \(n=3\) n = 3 the quaternionic version of G has been recently used to study the quaternionic slice regular function theory. This work extends the study of the G operator in two senses: a) Clifford’s analysis structure. The function theory induced by the operator \(\begin{aligned} {\mathcal {H}}_a (x) = {{\underline{a}}} ( {x}) \frac{\partial }{\partial x_0} - \sum _{i=1}^n \left( \sum _{j=1}^n a_j ( {x}) \frac{\partial (a^{-1})_i}{\partial y_j}\circ a ( {x}) \right) \frac{\partial }{\partial x_i}, \end{aligned}\) H a ( x ) = a ̲ ( x ) x 0 - i = 1 n j = 1 n a j ( x ) ( a - 1 ) i y j a ( x ) x i , where a is a function with certain properties with domain in \({\mathbb {R}}^{n+1}\) R n + 1 is presented extending the already known results of the G (if \(a=I\) a = I is the identity function we can see that \(G=-\underline{x}{\mathcal {H}}_I\) G = - x ̲ H I ) such as Splitting Lemma, Representations Theorem, Cauchy formula, a characterization of the zero sets of \({\mathcal {H}}_a\) H a and a power series development. Also, some properties of the material derivative: \(\begin{aligned} {D}_u = \frac{\partial }{\partial x_0} + \sum _{j=1}^n u_j \frac{\partial }{\partial x_j}, \end{aligned}\) D u = x 0 + j = 1 n u j x j , where u is a certain \({\mathbb {R}}^{n}\) R n -valued function with domains in \({\mathbb {R}}^{n}\) R n , or \({\mathbb {R}}^{n+1}\) R n + 1 , are presented as consequences of function theory induced by \({\mathcal {H}}_a\) H a . b) Structure of quaternionic analysis. In particular, the case \(n=3\) n = 3 is approached from the point of view of quaternionic analysis presenting results such as Splitting Lemma, Representations Theorem, Borel-Pompeiu, Stokes and Cauchy formulas, a conformal covariant property and a characterization of the zero sets of the quaternonic version of \({\mathcal {H}}_a\) H a and its consequences for \(D_u\) D u .