bound the expectation of max of sets of functions












0












$begingroup$


Let $Xinmathbb{R}^{ntimes d}$ be a random matrix, and ${m_k}_{k=1}^K, m_k in mathbb{R}^{d}$ be a fixed set of matrices. I was wondering, what is the expectation (or upper bound of the expectation) of



$mathbb{E}max_{k}{||Xm_k||_2^2}$



Any comment or hint will be appreciated!










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$endgroup$












  • $begingroup$
    For an upper bound, notice that $|M_kX|_2^2 leq |M_k|^2|X|_2^2$ (where our first norm is the matrix norm), so $max_k{|M_kX|^2_2} leq max_k{|M_k|^2}|X|_2^2$, and by the linearity of expectation, $mathbb{E}max_k{|M_kX|_2^2leq max_k{|M_k|^2}mathbb{E}|X|_2^2$.
    $endgroup$
    – user3482749
    Jan 16 at 23:18










  • $begingroup$
    Thanks for the comments! I wrote my question in a wrong way (now corrected), but I think your method is still applicable. Thanks a lot!
    $endgroup$
    – user3138073
    Jan 16 at 23:31
















0












$begingroup$


Let $Xinmathbb{R}^{ntimes d}$ be a random matrix, and ${m_k}_{k=1}^K, m_k in mathbb{R}^{d}$ be a fixed set of matrices. I was wondering, what is the expectation (or upper bound of the expectation) of



$mathbb{E}max_{k}{||Xm_k||_2^2}$



Any comment or hint will be appreciated!










share|cite|improve this question











$endgroup$












  • $begingroup$
    For an upper bound, notice that $|M_kX|_2^2 leq |M_k|^2|X|_2^2$ (where our first norm is the matrix norm), so $max_k{|M_kX|^2_2} leq max_k{|M_k|^2}|X|_2^2$, and by the linearity of expectation, $mathbb{E}max_k{|M_kX|_2^2leq max_k{|M_k|^2}mathbb{E}|X|_2^2$.
    $endgroup$
    – user3482749
    Jan 16 at 23:18










  • $begingroup$
    Thanks for the comments! I wrote my question in a wrong way (now corrected), but I think your method is still applicable. Thanks a lot!
    $endgroup$
    – user3138073
    Jan 16 at 23:31














0












0








0





$begingroup$


Let $Xinmathbb{R}^{ntimes d}$ be a random matrix, and ${m_k}_{k=1}^K, m_k in mathbb{R}^{d}$ be a fixed set of matrices. I was wondering, what is the expectation (or upper bound of the expectation) of



$mathbb{E}max_{k}{||Xm_k||_2^2}$



Any comment or hint will be appreciated!










share|cite|improve this question











$endgroup$




Let $Xinmathbb{R}^{ntimes d}$ be a random matrix, and ${m_k}_{k=1}^K, m_k in mathbb{R}^{d}$ be a fixed set of matrices. I was wondering, what is the expectation (or upper bound of the expectation) of



$mathbb{E}max_{k}{||Xm_k||_2^2}$



Any comment or hint will be appreciated!







probability probability-theory expected-value






share|cite|improve this question















share|cite|improve this question













share|cite|improve this question




share|cite|improve this question








edited Jan 16 at 23:30







user3138073

















asked Jan 16 at 23:13









user3138073user3138073

1858




1858












  • $begingroup$
    For an upper bound, notice that $|M_kX|_2^2 leq |M_k|^2|X|_2^2$ (where our first norm is the matrix norm), so $max_k{|M_kX|^2_2} leq max_k{|M_k|^2}|X|_2^2$, and by the linearity of expectation, $mathbb{E}max_k{|M_kX|_2^2leq max_k{|M_k|^2}mathbb{E}|X|_2^2$.
    $endgroup$
    – user3482749
    Jan 16 at 23:18










  • $begingroup$
    Thanks for the comments! I wrote my question in a wrong way (now corrected), but I think your method is still applicable. Thanks a lot!
    $endgroup$
    – user3138073
    Jan 16 at 23:31


















  • $begingroup$
    For an upper bound, notice that $|M_kX|_2^2 leq |M_k|^2|X|_2^2$ (where our first norm is the matrix norm), so $max_k{|M_kX|^2_2} leq max_k{|M_k|^2}|X|_2^2$, and by the linearity of expectation, $mathbb{E}max_k{|M_kX|_2^2leq max_k{|M_k|^2}mathbb{E}|X|_2^2$.
    $endgroup$
    – user3482749
    Jan 16 at 23:18










  • $begingroup$
    Thanks for the comments! I wrote my question in a wrong way (now corrected), but I think your method is still applicable. Thanks a lot!
    $endgroup$
    – user3138073
    Jan 16 at 23:31
















$begingroup$
For an upper bound, notice that $|M_kX|_2^2 leq |M_k|^2|X|_2^2$ (where our first norm is the matrix norm), so $max_k{|M_kX|^2_2} leq max_k{|M_k|^2}|X|_2^2$, and by the linearity of expectation, $mathbb{E}max_k{|M_kX|_2^2leq max_k{|M_k|^2}mathbb{E}|X|_2^2$.
$endgroup$
– user3482749
Jan 16 at 23:18




$begingroup$
For an upper bound, notice that $|M_kX|_2^2 leq |M_k|^2|X|_2^2$ (where our first norm is the matrix norm), so $max_k{|M_kX|^2_2} leq max_k{|M_k|^2}|X|_2^2$, and by the linearity of expectation, $mathbb{E}max_k{|M_kX|_2^2leq max_k{|M_k|^2}mathbb{E}|X|_2^2$.
$endgroup$
– user3482749
Jan 16 at 23:18












$begingroup$
Thanks for the comments! I wrote my question in a wrong way (now corrected), but I think your method is still applicable. Thanks a lot!
$endgroup$
– user3138073
Jan 16 at 23:31




$begingroup$
Thanks for the comments! I wrote my question in a wrong way (now corrected), but I think your method is still applicable. Thanks a lot!
$endgroup$
– user3138073
Jan 16 at 23:31










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