author_facet Diaz, R.
Diaz, R.
author Diaz, R.
spellingShingle Diaz, R.
Proceedings of the American Mathematical Society
A Runge theorem for solutions of the heat equation
Applied Mathematics
General Mathematics
author_sort diaz, r.
spelling Diaz, R. 0002-9939 1088-6826 American Mathematical Society (AMS) Applied Mathematics General Mathematics http://dx.doi.org/10.1090/s0002-9939-1980-0587944-2 <p>Let <inline-formula content-type="math/mathml"> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="normal upper Omega 1"> <mml:semantics> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:msub> <mml:mi mathvariant="normal">Ω<!-- Ω --></mml:mi> <mml:mn>1</mml:mn> </mml:msub> </mml:mrow> <mml:annotation encoding="application/x-tex">{\Omega _1}</mml:annotation> </mml:semantics> </mml:math> </inline-formula> and <inline-formula content-type="math/mathml"> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="normal upper Omega 2"> <mml:semantics> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:msub> <mml:mi mathvariant="normal">Ω<!-- Ω --></mml:mi> <mml:mn>2</mml:mn> </mml:msub> </mml:mrow> <mml:annotation encoding="application/x-tex">{\Omega _2}</mml:annotation> </mml:semantics> </mml:math> </inline-formula> be open sets in <inline-formula content-type="math/mathml"> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="upper R Superscript n"> <mml:semantics> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:msup> <mml:mi>R</mml:mi> <mml:mi>n</mml:mi> </mml:msup> </mml:mrow> <mml:annotation encoding="application/x-tex">{R^n}</mml:annotation> </mml:semantics> </mml:math> </inline-formula> such that <inline-formula content-type="math/mathml"> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="normal upper Omega 1 subset-of normal upper Omega 2"> <mml:semantics> <mml:mrow> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:msub> <mml:mi mathvariant="normal">Ω<!-- Ω --></mml:mi> <mml:mn>1</mml:mn> </mml:msub> </mml:mrow> <mml:mo>⊂<!-- ⊂ --></mml:mo> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:msub> <mml:mi mathvariant="normal">Ω<!-- Ω --></mml:mi> <mml:mn>2</mml:mn> </mml:msub> </mml:mrow> </mml:mrow> <mml:annotation encoding="application/x-tex">{\Omega _1} \subset {\Omega _2}</mml:annotation> </mml:semantics> </mml:math> </inline-formula>. Every solution of the heat equation on <inline-formula content-type="math/mathml"> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="normal upper Omega 1"> <mml:semantics> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:msub> <mml:mi mathvariant="normal">Ω<!-- Ω --></mml:mi> <mml:mn>1</mml:mn> </mml:msub> </mml:mrow> <mml:annotation encoding="application/x-tex">{\Omega _1}</mml:annotation> </mml:semantics> </mml:math> </inline-formula> admits approximation on the compact subsets of <inline-formula content-type="math/mathml"> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="normal upper Omega 1"> <mml:semantics> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:msub> <mml:mi mathvariant="normal">Ω<!-- Ω --></mml:mi> <mml:mn>1</mml:mn> </mml:msub> </mml:mrow> <mml:annotation encoding="application/x-tex">{\Omega _1}</mml:annotation> </mml:semantics> </mml:math> </inline-formula> by functions which satisfy the heat equation throughout <inline-formula content-type="math/mathml"> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="normal upper Omega 2"> <mml:semantics> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:msub> <mml:mi mathvariant="normal">Ω<!-- Ω --></mml:mi> <mml:mn>2</mml:mn> </mml:msub> </mml:mrow> <mml:annotation encoding="application/x-tex">{\Omega _2}</mml:annotation> </mml:semantics> </mml:math> </inline-formula> if and only if this topological condition is met: For every hyperplane <inline-formula content-type="math/mathml"> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="pi"> <mml:semantics> <mml:mi>π<!-- π --></mml:mi> <mml:annotation encoding="application/x-tex">\pi</mml:annotation> </mml:semantics> </mml:math> </inline-formula> in <inline-formula content-type="math/mathml"> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="upper R Superscript n"> <mml:semantics> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:msup> <mml:mi>R</mml:mi> <mml:mi>n</mml:mi> </mml:msup> </mml:mrow> <mml:annotation encoding="application/x-tex">{R^n}</mml:annotation> </mml:semantics> </mml:math> </inline-formula> orthogonal to the time axis, every compact component of <inline-formula content-type="math/mathml"> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="pi minus normal upper Omega 1"> <mml:semantics> <mml:mrow> <mml:mi>π<!-- π --></mml:mi> <mml:mi class="MJX-variant" mathvariant="normal">∖<!-- ∖ --></mml:mi> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:msub> <mml:mi mathvariant="normal">Ω<!-- Ω --></mml:mi> <mml:mn>1</mml:mn> </mml:msub> </mml:mrow> </mml:mrow> <mml:annotation encoding="application/x-tex">\pi \backslash {\Omega _1}</mml:annotation> </mml:semantics> </mml:math> </inline-formula> contains a compact component of <inline-formula content-type="math/mathml"> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="pi minus normal upper Omega 2"> <mml:semantics> <mml:mrow> <mml:mi>π<!-- π --></mml:mi> <mml:mi class="MJX-variant" mathvariant="normal">∖<!-- ∖ --></mml:mi> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:msub> <mml:mi mathvariant="normal">Ω<!-- Ω --></mml:mi> <mml:mn>2</mml:mn> </mml:msub> </mml:mrow> </mml:mrow> <mml:annotation encoding="application/x-tex">\pi \backslash {\Omega _2}</mml:annotation> </mml:semantics> </mml:math> </inline-formula>.</p> A Runge theorem for solutions of the heat equation Proceedings of the American Mathematical Society
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imprint_str_mv American Mathematical Society (AMS), 1980
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issn_str_mv 0002-9939
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match_str diaz1980arungetheoremforsolutionsoftheheatequation
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publisher American Mathematical Society (AMS)
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series Proceedings of the American Mathematical Society
source_id 49
title A Runge theorem for solutions of the heat equation
title_unstemmed A Runge theorem for solutions of the heat equation
title_full A Runge theorem for solutions of the heat equation
title_fullStr A Runge theorem for solutions of the heat equation
title_full_unstemmed A Runge theorem for solutions of the heat equation
title_short A Runge theorem for solutions of the heat equation
title_sort a runge theorem for solutions of the heat equation
topic Applied Mathematics
General Mathematics
url http://dx.doi.org/10.1090/s0002-9939-1980-0587944-2
publishDate 1980
physical 643-646
description <p>Let <inline-formula content-type="math/mathml"> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="normal upper Omega 1"> <mml:semantics> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:msub> <mml:mi mathvariant="normal">Ω<!-- Ω --></mml:mi> <mml:mn>1</mml:mn> </mml:msub> </mml:mrow> <mml:annotation encoding="application/x-tex">{\Omega _1}</mml:annotation> </mml:semantics> </mml:math> </inline-formula> and <inline-formula content-type="math/mathml"> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="normal upper Omega 2"> <mml:semantics> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:msub> <mml:mi mathvariant="normal">Ω<!-- Ω --></mml:mi> <mml:mn>2</mml:mn> </mml:msub> </mml:mrow> <mml:annotation encoding="application/x-tex">{\Omega _2}</mml:annotation> </mml:semantics> </mml:math> </inline-formula> be open sets in <inline-formula content-type="math/mathml"> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="upper R Superscript n"> <mml:semantics> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:msup> <mml:mi>R</mml:mi> <mml:mi>n</mml:mi> </mml:msup> </mml:mrow> <mml:annotation encoding="application/x-tex">{R^n}</mml:annotation> </mml:semantics> </mml:math> </inline-formula> such that <inline-formula content-type="math/mathml"> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="normal upper Omega 1 subset-of normal upper Omega 2"> <mml:semantics> <mml:mrow> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:msub> <mml:mi mathvariant="normal">Ω<!-- Ω --></mml:mi> <mml:mn>1</mml:mn> </mml:msub> </mml:mrow> <mml:mo>⊂<!-- ⊂ --></mml:mo> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:msub> <mml:mi mathvariant="normal">Ω<!-- Ω --></mml:mi> <mml:mn>2</mml:mn> </mml:msub> </mml:mrow> </mml:mrow> <mml:annotation encoding="application/x-tex">{\Omega _1} \subset {\Omega _2}</mml:annotation> </mml:semantics> </mml:math> </inline-formula>. Every solution of the heat equation on <inline-formula content-type="math/mathml"> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="normal upper Omega 1"> <mml:semantics> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:msub> <mml:mi mathvariant="normal">Ω<!-- Ω --></mml:mi> <mml:mn>1</mml:mn> </mml:msub> </mml:mrow> <mml:annotation encoding="application/x-tex">{\Omega _1}</mml:annotation> </mml:semantics> </mml:math> </inline-formula> admits approximation on the compact subsets of <inline-formula content-type="math/mathml"> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="normal upper Omega 1"> <mml:semantics> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:msub> <mml:mi mathvariant="normal">Ω<!-- Ω --></mml:mi> <mml:mn>1</mml:mn> </mml:msub> </mml:mrow> <mml:annotation encoding="application/x-tex">{\Omega _1}</mml:annotation> </mml:semantics> </mml:math> </inline-formula> by functions which satisfy the heat equation throughout <inline-formula content-type="math/mathml"> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="normal upper Omega 2"> <mml:semantics> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:msub> <mml:mi mathvariant="normal">Ω<!-- Ω --></mml:mi> <mml:mn>2</mml:mn> </mml:msub> </mml:mrow> <mml:annotation encoding="application/x-tex">{\Omega _2}</mml:annotation> </mml:semantics> </mml:math> </inline-formula> if and only if this topological condition is met: For every hyperplane <inline-formula content-type="math/mathml"> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="pi"> <mml:semantics> <mml:mi>π<!-- π --></mml:mi> <mml:annotation encoding="application/x-tex">\pi</mml:annotation> </mml:semantics> </mml:math> </inline-formula> in <inline-formula content-type="math/mathml"> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="upper R Superscript n"> <mml:semantics> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:msup> <mml:mi>R</mml:mi> <mml:mi>n</mml:mi> </mml:msup> </mml:mrow> <mml:annotation encoding="application/x-tex">{R^n}</mml:annotation> </mml:semantics> </mml:math> </inline-formula> orthogonal to the time axis, every compact component of <inline-formula content-type="math/mathml"> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="pi minus normal upper Omega 1"> <mml:semantics> <mml:mrow> <mml:mi>π<!-- π --></mml:mi> <mml:mi class="MJX-variant" mathvariant="normal">∖<!-- ∖ --></mml:mi> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:msub> <mml:mi mathvariant="normal">Ω<!-- Ω --></mml:mi> <mml:mn>1</mml:mn> </mml:msub> </mml:mrow> </mml:mrow> <mml:annotation encoding="application/x-tex">\pi \backslash {\Omega _1}</mml:annotation> </mml:semantics> </mml:math> </inline-formula> contains a compact component of <inline-formula content-type="math/mathml"> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="pi minus normal upper Omega 2"> <mml:semantics> <mml:mrow> <mml:mi>π<!-- π --></mml:mi> <mml:mi class="MJX-variant" mathvariant="normal">∖<!-- ∖ --></mml:mi> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:msub> <mml:mi mathvariant="normal">Ω<!-- Ω --></mml:mi> <mml:mn>2</mml:mn> </mml:msub> </mml:mrow> </mml:mrow> <mml:annotation encoding="application/x-tex">\pi \backslash {\Omega _2}</mml:annotation> </mml:semantics> </mml:math> </inline-formula>.</p>
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author Diaz, R.
author_facet Diaz, R., Diaz, R.
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container_title Proceedings of the American Mathematical Society
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description <p>Let <inline-formula content-type="math/mathml"> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="normal upper Omega 1"> <mml:semantics> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:msub> <mml:mi mathvariant="normal">Ω<!-- Ω --></mml:mi> <mml:mn>1</mml:mn> </mml:msub> </mml:mrow> <mml:annotation encoding="application/x-tex">{\Omega _1}</mml:annotation> </mml:semantics> </mml:math> </inline-formula> and <inline-formula content-type="math/mathml"> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="normal upper Omega 2"> <mml:semantics> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:msub> <mml:mi mathvariant="normal">Ω<!-- Ω --></mml:mi> <mml:mn>2</mml:mn> </mml:msub> </mml:mrow> <mml:annotation encoding="application/x-tex">{\Omega _2}</mml:annotation> </mml:semantics> </mml:math> </inline-formula> be open sets in <inline-formula content-type="math/mathml"> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="upper R Superscript n"> <mml:semantics> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:msup> <mml:mi>R</mml:mi> <mml:mi>n</mml:mi> </mml:msup> </mml:mrow> <mml:annotation encoding="application/x-tex">{R^n}</mml:annotation> </mml:semantics> </mml:math> </inline-formula> such that <inline-formula content-type="math/mathml"> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="normal upper Omega 1 subset-of normal upper Omega 2"> <mml:semantics> <mml:mrow> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:msub> <mml:mi mathvariant="normal">Ω<!-- Ω --></mml:mi> <mml:mn>1</mml:mn> </mml:msub> </mml:mrow> <mml:mo>⊂<!-- ⊂ --></mml:mo> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:msub> <mml:mi mathvariant="normal">Ω<!-- Ω --></mml:mi> <mml:mn>2</mml:mn> </mml:msub> </mml:mrow> </mml:mrow> <mml:annotation encoding="application/x-tex">{\Omega _1} \subset {\Omega _2}</mml:annotation> </mml:semantics> </mml:math> </inline-formula>. Every solution of the heat equation on <inline-formula content-type="math/mathml"> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="normal upper Omega 1"> <mml:semantics> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:msub> <mml:mi mathvariant="normal">Ω<!-- Ω --></mml:mi> <mml:mn>1</mml:mn> </mml:msub> </mml:mrow> <mml:annotation encoding="application/x-tex">{\Omega _1}</mml:annotation> </mml:semantics> </mml:math> </inline-formula> admits approximation on the compact subsets of <inline-formula content-type="math/mathml"> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="normal upper Omega 1"> <mml:semantics> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:msub> <mml:mi mathvariant="normal">Ω<!-- Ω --></mml:mi> <mml:mn>1</mml:mn> </mml:msub> </mml:mrow> <mml:annotation encoding="application/x-tex">{\Omega _1}</mml:annotation> </mml:semantics> </mml:math> </inline-formula> by functions which satisfy the heat equation throughout <inline-formula content-type="math/mathml"> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="normal upper Omega 2"> <mml:semantics> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:msub> <mml:mi mathvariant="normal">Ω<!-- Ω --></mml:mi> <mml:mn>2</mml:mn> </mml:msub> </mml:mrow> <mml:annotation encoding="application/x-tex">{\Omega _2}</mml:annotation> </mml:semantics> </mml:math> </inline-formula> if and only if this topological condition is met: For every hyperplane <inline-formula content-type="math/mathml"> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="pi"> <mml:semantics> <mml:mi>π<!-- π --></mml:mi> <mml:annotation encoding="application/x-tex">\pi</mml:annotation> </mml:semantics> </mml:math> </inline-formula> in <inline-formula content-type="math/mathml"> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="upper R Superscript n"> <mml:semantics> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:msup> <mml:mi>R</mml:mi> <mml:mi>n</mml:mi> </mml:msup> </mml:mrow> <mml:annotation encoding="application/x-tex">{R^n}</mml:annotation> </mml:semantics> </mml:math> </inline-formula> orthogonal to the time axis, every compact component of <inline-formula content-type="math/mathml"> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="pi minus normal upper Omega 1"> <mml:semantics> <mml:mrow> <mml:mi>π<!-- π --></mml:mi> <mml:mi class="MJX-variant" mathvariant="normal">∖<!-- ∖ --></mml:mi> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:msub> <mml:mi mathvariant="normal">Ω<!-- Ω --></mml:mi> <mml:mn>1</mml:mn> </mml:msub> </mml:mrow> </mml:mrow> <mml:annotation encoding="application/x-tex">\pi \backslash {\Omega _1}</mml:annotation> </mml:semantics> </mml:math> </inline-formula> contains a compact component of <inline-formula content-type="math/mathml"> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="pi minus normal upper Omega 2"> <mml:semantics> <mml:mrow> <mml:mi>π<!-- π --></mml:mi> <mml:mi class="MJX-variant" mathvariant="normal">∖<!-- ∖ --></mml:mi> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:msub> <mml:mi mathvariant="normal">Ω<!-- Ω --></mml:mi> <mml:mn>2</mml:mn> </mml:msub> </mml:mrow> </mml:mrow> <mml:annotation encoding="application/x-tex">\pi \backslash {\Omega _2}</mml:annotation> </mml:semantics> </mml:math> </inline-formula>.</p>
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series Proceedings of the American Mathematical Society
source_id 49
spelling Diaz, R. 0002-9939 1088-6826 American Mathematical Society (AMS) Applied Mathematics General Mathematics http://dx.doi.org/10.1090/s0002-9939-1980-0587944-2 <p>Let <inline-formula content-type="math/mathml"> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="normal upper Omega 1"> <mml:semantics> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:msub> <mml:mi mathvariant="normal">Ω<!-- Ω --></mml:mi> <mml:mn>1</mml:mn> </mml:msub> </mml:mrow> <mml:annotation encoding="application/x-tex">{\Omega _1}</mml:annotation> </mml:semantics> </mml:math> </inline-formula> and <inline-formula content-type="math/mathml"> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="normal upper Omega 2"> <mml:semantics> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:msub> <mml:mi mathvariant="normal">Ω<!-- Ω --></mml:mi> <mml:mn>2</mml:mn> </mml:msub> </mml:mrow> <mml:annotation encoding="application/x-tex">{\Omega _2}</mml:annotation> </mml:semantics> </mml:math> </inline-formula> be open sets in <inline-formula content-type="math/mathml"> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="upper R Superscript n"> <mml:semantics> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:msup> <mml:mi>R</mml:mi> <mml:mi>n</mml:mi> </mml:msup> </mml:mrow> <mml:annotation encoding="application/x-tex">{R^n}</mml:annotation> </mml:semantics> </mml:math> </inline-formula> such that <inline-formula content-type="math/mathml"> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="normal upper Omega 1 subset-of normal upper Omega 2"> <mml:semantics> <mml:mrow> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:msub> <mml:mi mathvariant="normal">Ω<!-- Ω --></mml:mi> <mml:mn>1</mml:mn> </mml:msub> </mml:mrow> <mml:mo>⊂<!-- ⊂ --></mml:mo> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:msub> <mml:mi mathvariant="normal">Ω<!-- Ω --></mml:mi> <mml:mn>2</mml:mn> </mml:msub> </mml:mrow> </mml:mrow> <mml:annotation encoding="application/x-tex">{\Omega _1} \subset {\Omega _2}</mml:annotation> </mml:semantics> </mml:math> </inline-formula>. Every solution of the heat equation on <inline-formula content-type="math/mathml"> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="normal upper Omega 1"> <mml:semantics> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:msub> <mml:mi mathvariant="normal">Ω<!-- Ω --></mml:mi> <mml:mn>1</mml:mn> </mml:msub> </mml:mrow> <mml:annotation encoding="application/x-tex">{\Omega _1}</mml:annotation> </mml:semantics> </mml:math> </inline-formula> admits approximation on the compact subsets of <inline-formula content-type="math/mathml"> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="normal upper Omega 1"> <mml:semantics> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:msub> <mml:mi mathvariant="normal">Ω<!-- Ω --></mml:mi> <mml:mn>1</mml:mn> </mml:msub> </mml:mrow> <mml:annotation encoding="application/x-tex">{\Omega _1}</mml:annotation> </mml:semantics> </mml:math> </inline-formula> by functions which satisfy the heat equation throughout <inline-formula content-type="math/mathml"> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="normal upper Omega 2"> <mml:semantics> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:msub> <mml:mi mathvariant="normal">Ω<!-- Ω --></mml:mi> <mml:mn>2</mml:mn> </mml:msub> </mml:mrow> <mml:annotation encoding="application/x-tex">{\Omega _2}</mml:annotation> </mml:semantics> </mml:math> </inline-formula> if and only if this topological condition is met: For every hyperplane <inline-formula content-type="math/mathml"> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="pi"> <mml:semantics> <mml:mi>π<!-- π --></mml:mi> <mml:annotation encoding="application/x-tex">\pi</mml:annotation> </mml:semantics> </mml:math> </inline-formula> in <inline-formula content-type="math/mathml"> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="upper R Superscript n"> <mml:semantics> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:msup> <mml:mi>R</mml:mi> <mml:mi>n</mml:mi> </mml:msup> </mml:mrow> <mml:annotation encoding="application/x-tex">{R^n}</mml:annotation> </mml:semantics> </mml:math> </inline-formula> orthogonal to the time axis, every compact component of <inline-formula content-type="math/mathml"> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="pi minus normal upper Omega 1"> <mml:semantics> <mml:mrow> <mml:mi>π<!-- π --></mml:mi> <mml:mi class="MJX-variant" mathvariant="normal">∖<!-- ∖ --></mml:mi> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:msub> <mml:mi mathvariant="normal">Ω<!-- Ω --></mml:mi> <mml:mn>1</mml:mn> </mml:msub> </mml:mrow> </mml:mrow> <mml:annotation encoding="application/x-tex">\pi \backslash {\Omega _1}</mml:annotation> </mml:semantics> </mml:math> </inline-formula> contains a compact component of <inline-formula content-type="math/mathml"> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="pi minus normal upper Omega 2"> <mml:semantics> <mml:mrow> <mml:mi>π<!-- π --></mml:mi> <mml:mi class="MJX-variant" mathvariant="normal">∖<!-- ∖ --></mml:mi> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:msub> <mml:mi mathvariant="normal">Ω<!-- Ω --></mml:mi> <mml:mn>2</mml:mn> </mml:msub> </mml:mrow> </mml:mrow> <mml:annotation encoding="application/x-tex">\pi \backslash {\Omega _2}</mml:annotation> </mml:semantics> </mml:math> </inline-formula>.</p> A Runge theorem for solutions of the heat equation Proceedings of the American Mathematical Society
spellingShingle Diaz, R., Proceedings of the American Mathematical Society, A Runge theorem for solutions of the heat equation, Applied Mathematics, General Mathematics
title A Runge theorem for solutions of the heat equation
title_full A Runge theorem for solutions of the heat equation
title_fullStr A Runge theorem for solutions of the heat equation
title_full_unstemmed A Runge theorem for solutions of the heat equation
title_short A Runge theorem for solutions of the heat equation
title_sort a runge theorem for solutions of the heat equation
title_unstemmed A Runge theorem for solutions of the heat equation
topic Applied Mathematics, General Mathematics
url http://dx.doi.org/10.1090/s0002-9939-1980-0587944-2