<p>We consider the following extremal problem: <i>Among all matrices that map a given point x of the Euclidean space</i> <InlineEquation ID="IEq1"> <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> <i>to a given point b of the Euclidean space</i> <InlineEquation ID="IEq2"> <EquationSource Format="TEX">\(\mathbb {R}^m\)</EquationSource> <EquationSource Format="MATHML"><math> <msup> <mrow> <mi mathvariant="double-struck">R</mi> </mrow> <mi>m</mi> </msup> </math></EquationSource> </InlineEquation>, <i>find a matrix of minimal norm.</i> The article uses the Hölder norm of vectors and matrices depending on a parameter <i>p</i>. It is shown that for every <InlineEquation ID="IEq3"> <EquationSource Format="TEX">\(p \in (1, +\infty )\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>p</mi> <mo>∈</mo> <mo stretchy="false">(</mo> <mn>1</mn> <mo>,</mo> <mo>+</mo> <mi>∞</mi> <mo stretchy="false">)</mo> </mrow> </math></EquationSource> </InlineEquation> there exists a unique solution of the stated problem and an explicit formula for it is derived. Limits of the optimal matrix are found as <i>p</i> approaches the boundary values <InlineEquation ID="IEq4"> <EquationSource Format="TEX">\(p \rightarrow 1\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>p</mi> <mo stretchy="false">→</mo> <mn>1</mn> </mrow> </math></EquationSource> </InlineEquation> and <InlineEquation ID="IEq5"> <EquationSource Format="TEX">\(p \rightarrow +\infty \)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>p</mi> <mo stretchy="false">→</mo> <mo>+</mo> <mi>∞</mi> </mrow> </math></EquationSource> </InlineEquation>. It is established that the limiting matrices are solutions of the corresponding limiting extremal problems. However, unlike the case <InlineEquation ID="IEq6"> <EquationSource Format="TEX">\(p \in (1, +\infty )\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>p</mi> <mo>∈</mo> <mo stretchy="false">(</mo> <mn>1</mn> <mo>,</mo> <mo>+</mo> <mi>∞</mi> <mo stretchy="false">)</mo> </mrow> </math></EquationSource> </InlineEquation>, uniqueness of these limiting solutions is not guaranteed. A full description of the entire set of solutions of the nonsmooth limiting problems is given.</p>

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Limit Theorems in the Problem of Optimal Linear Transformation

  • V. N. Malozemov,
  • A. V. Petrov

摘要

We consider the following extremal problem: Among all matrices that map a given point x of the Euclidean space \(\mathbb {R}^n\) R n to a given point b of the Euclidean space \(\mathbb {R}^m\) R m , find a matrix of minimal norm. The article uses the Hölder norm of vectors and matrices depending on a parameter p. It is shown that for every \(p \in (1, +\infty )\) p ( 1 , + ) there exists a unique solution of the stated problem and an explicit formula for it is derived. Limits of the optimal matrix are found as p approaches the boundary values \(p \rightarrow 1\) p 1 and \(p \rightarrow +\infty \) p + . It is established that the limiting matrices are solutions of the corresponding limiting extremal problems. However, unlike the case \(p \in (1, +\infty )\) p ( 1 , + ) , uniqueness of these limiting solutions is not guaranteed. A full description of the entire set of solutions of the nonsmooth limiting problems is given.