Bad convex functions











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Why are functions of the form $ f_{m} (x) = eta_{p+1}(A_m x) - x_1$ bad, where $eta_{p+1} = frac{1}{p+1}sum_{i=1}^{n}(x_i)^{p+1}$, $A_m = begin{pmatrix}U_m & 0 \ 0 &I_{n-m} end{pmatrix}$, $U_m = begin{pmatrix} 1 & -1 & 0& ... \
0&1&-1&0&....\
&&...&&\
0&...&0&1 end{pmatrix} in mathbb{R}^{mtimes m}$
.



In https://arxiv.org/pdf/1705.07260.pdf and https://alfresco.uclouvain.be/alfresco/service/guest/streamDownload/workspace/SpacesStore/aabc2323-0bc1-40d4-9653-1c29971e7bd8/coredp2018_05web.pdf?guest=true this family of functions are used for estimate lower bound complexity.



I don't really understand explanation from first article. Could someone explain more clearly?










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    Why are functions of the form $ f_{m} (x) = eta_{p+1}(A_m x) - x_1$ bad, where $eta_{p+1} = frac{1}{p+1}sum_{i=1}^{n}(x_i)^{p+1}$, $A_m = begin{pmatrix}U_m & 0 \ 0 &I_{n-m} end{pmatrix}$, $U_m = begin{pmatrix} 1 & -1 & 0& ... \
    0&1&-1&0&....\
    &&...&&\
    0&...&0&1 end{pmatrix} in mathbb{R}^{mtimes m}$
    .



    In https://arxiv.org/pdf/1705.07260.pdf and https://alfresco.uclouvain.be/alfresco/service/guest/streamDownload/workspace/SpacesStore/aabc2323-0bc1-40d4-9653-1c29971e7bd8/coredp2018_05web.pdf?guest=true this family of functions are used for estimate lower bound complexity.



    I don't really understand explanation from first article. Could someone explain more clearly?










    share|cite|improve this question


























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      down vote

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      Why are functions of the form $ f_{m} (x) = eta_{p+1}(A_m x) - x_1$ bad, where $eta_{p+1} = frac{1}{p+1}sum_{i=1}^{n}(x_i)^{p+1}$, $A_m = begin{pmatrix}U_m & 0 \ 0 &I_{n-m} end{pmatrix}$, $U_m = begin{pmatrix} 1 & -1 & 0& ... \
      0&1&-1&0&....\
      &&...&&\
      0&...&0&1 end{pmatrix} in mathbb{R}^{mtimes m}$
      .



      In https://arxiv.org/pdf/1705.07260.pdf and https://alfresco.uclouvain.be/alfresco/service/guest/streamDownload/workspace/SpacesStore/aabc2323-0bc1-40d4-9653-1c29971e7bd8/coredp2018_05web.pdf?guest=true this family of functions are used for estimate lower bound complexity.



      I don't really understand explanation from first article. Could someone explain more clearly?










      share|cite|improve this question















      Why are functions of the form $ f_{m} (x) = eta_{p+1}(A_m x) - x_1$ bad, where $eta_{p+1} = frac{1}{p+1}sum_{i=1}^{n}(x_i)^{p+1}$, $A_m = begin{pmatrix}U_m & 0 \ 0 &I_{n-m} end{pmatrix}$, $U_m = begin{pmatrix} 1 & -1 & 0& ... \
      0&1&-1&0&....\
      &&...&&\
      0&...&0&1 end{pmatrix} in mathbb{R}^{mtimes m}$
      .



      In https://arxiv.org/pdf/1705.07260.pdf and https://alfresco.uclouvain.be/alfresco/service/guest/streamDownload/workspace/SpacesStore/aabc2323-0bc1-40d4-9653-1c29971e7bd8/coredp2018_05web.pdf?guest=true this family of functions are used for estimate lower bound complexity.



      I don't really understand explanation from first article. Could someone explain more clearly?







      optimization convex-optimization numerical-optimization






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      edited Nov 16 at 16:33

























      asked Nov 1 at 22:16









      Albert Nagapetyan

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