<p>We consider the randomly weighted sums <InlineEquation ID="IEq1"> <EquationSource Format="TEX">\({\sum }_{i=1}^{m}{\Theta }_{i}{X}_{i}\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <msubsup> <mo>∑</mo> <mrow> <mi>i</mi> <mo>=</mo> <mn>1</mn> </mrow> <mi>m</mi> </msubsup> <msub> <mi mathvariant="normal">Θ</mi> <mi>i</mi> </msub> <msub> <mi>X</mi> <mi>i</mi> </msub> </mrow> </math></EquationSource> </InlineEquation> and <InlineEquation ID="IEq2"> <EquationSource Format="TEX">\({\sum }_{j=1}^{n}{\theta }_{j}{Y}_{j}\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <msubsup> <mo>∑</mo> <mrow> <mi>j</mi> <mo>=</mo> <mn>1</mn> </mrow> <mi>n</mi> </msubsup> <msub> <mi>θ</mi> <mi>j</mi> </msub> <msub> <mi>Y</mi> <mi>j</mi> </msub> </mrow> </math></EquationSource> </InlineEquation> for <i>m, n</i> ∈ℕ, where the real-valued random variables {<i>X</i><sub><i>i</i></sub>; <i>i</i> ∈ ℕ} and {<i>Y</i><sub><i>j</i></sub>; <i>j</i> ∈ ℕ}, possibly dependent, have heavy-tailed distributions, and the random weights <i>{Θ</i><sub><i>i</i></sub><i>, θ</i><sub><i>j</i></sub>; <i>i, j</i> ∈ ℕ} are nonnegative and arbitrarily dependent, but the sequences {<i>X</i><sub><i>i</i></sub>; <i>i</i> ∈ N}, {<i>Y</i><sub><i>j</i></sub>; <i>j</i> ∈ ℕ}<i>,</i> and {<i>Θ</i><sub><i>i</i></sub><i>, θ</i><sub><i>j</i></sub>; <i>i, j</i> ∈ℕ} are mutually independent. Under some mild conditions on the random weights, we derive the asymptotics of the joint tail probability of the two randomly weighted sums, in which the primary random variables satisfy some dependence assumptions.</p>

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Asymptotics for the joint tail probability of bidimensional randomly weighted sums of dependent and heavy-tailed random variables

  • Dawei Lu,
  • Yangyang Chen,
  • Lina Wang

摘要

We consider the randomly weighted sums \({\sum }_{i=1}^{m}{\Theta }_{i}{X}_{i}\) i = 1 m Θ i X i and \({\sum }_{j=1}^{n}{\theta }_{j}{Y}_{j}\) j = 1 n θ j Y j for m, n ∈ℕ, where the real-valued random variables {Xi; i ∈ ℕ} and {Yj; j ∈ ℕ}, possibly dependent, have heavy-tailed distributions, and the random weights i, θj; i, j ∈ ℕ} are nonnegative and arbitrarily dependent, but the sequences {Xi; i ∈ N}, {Yj; j ∈ ℕ}, and {Θi, θj; i, j ∈ℕ} are mutually independent. Under some mild conditions on the random weights, we derive the asymptotics of the joint tail probability of the two randomly weighted sums, in which the primary random variables satisfy some dependence assumptions.