What does that mean support of a distribution is contained in unit ball?












1












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In page 4, part 2 of assumption I in On the Regret Minimization of Nonconvex Online Gradient Ascent for Online PCA, the papers says "the support of $D$ is contained in a Euclidean ball of radius $R$ centered at the origin, i.e.,"
$$
sup_{textbf{q} in text{support}(D)} |textbf{q}|_2 leq R
$$



where $D$ is a distribution and $textbf{q}$'s are sampled i.i.d from $D$.



What is the meaning of that assumption? Could you elaborate it intuitively for me? What is the significance of such an assumption?










share|cite|improve this question









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    1












    $begingroup$


    In page 4, part 2 of assumption I in On the Regret Minimization of Nonconvex Online Gradient Ascent for Online PCA, the papers says "the support of $D$ is contained in a Euclidean ball of radius $R$ centered at the origin, i.e.,"
    $$
    sup_{textbf{q} in text{support}(D)} |textbf{q}|_2 leq R
    $$



    where $D$ is a distribution and $textbf{q}$'s are sampled i.i.d from $D$.



    What is the meaning of that assumption? Could you elaborate it intuitively for me? What is the significance of such an assumption?










    share|cite|improve this question









    $endgroup$















      1












      1








      1





      $begingroup$


      In page 4, part 2 of assumption I in On the Regret Minimization of Nonconvex Online Gradient Ascent for Online PCA, the papers says "the support of $D$ is contained in a Euclidean ball of radius $R$ centered at the origin, i.e.,"
      $$
      sup_{textbf{q} in text{support}(D)} |textbf{q}|_2 leq R
      $$



      where $D$ is a distribution and $textbf{q}$'s are sampled i.i.d from $D$.



      What is the meaning of that assumption? Could you elaborate it intuitively for me? What is the significance of such an assumption?










      share|cite|improve this question









      $endgroup$




      In page 4, part 2 of assumption I in On the Regret Minimization of Nonconvex Online Gradient Ascent for Online PCA, the papers says "the support of $D$ is contained in a Euclidean ball of radius $R$ centered at the origin, i.e.,"
      $$
      sup_{textbf{q} in text{support}(D)} |textbf{q}|_2 leq R
      $$



      where $D$ is a distribution and $textbf{q}$'s are sampled i.i.d from $D$.



      What is the meaning of that assumption? Could you elaborate it intuitively for me? What is the significance of such an assumption?







      probability statistics probability-distributions definition






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      asked Dec 27 '18 at 0:40









      SaeedSaeed

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      1,036310






















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          $begingroup$

          Roughly speaking, the support of a distribution is a closed set that contains [as subsets] all the sets with positive probability. For example, the uniform distribution on $[0,1]$ has support $[0,1]$, the exponential distribution has support $[0, infty)$, and the Gaussian distribution has support $mathbb{R}$. See the Wikipedia link for a more rigorous definition.



          So $text{support}(D)$ is a set, and the statement is simply saying $text{support}(D) subseteq B_R$ where $B_R$ is the Euclidean ball of radius $R$ centered at the origin. The inequality written in your question is equivalent: it simply states that all elements in the set $text{support}(D)$ have Euclidean norm $le R$.



          Long story short, the assumption is saying that the distribution $D$ gives zero probability to subsets lying outside of the Euclidean ball of radius $R$.






          share|cite|improve this answer









          $endgroup$













          • $begingroup$
            Thank you so much. It was very intuitive, specially the conclusion. Is this assumption something as we assume the norm of decision variable is less than $M$ in optimization?
            $endgroup$
            – Saeed
            Dec 27 '18 at 1:00











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          1 Answer
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          active

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          1












          $begingroup$

          Roughly speaking, the support of a distribution is a closed set that contains [as subsets] all the sets with positive probability. For example, the uniform distribution on $[0,1]$ has support $[0,1]$, the exponential distribution has support $[0, infty)$, and the Gaussian distribution has support $mathbb{R}$. See the Wikipedia link for a more rigorous definition.



          So $text{support}(D)$ is a set, and the statement is simply saying $text{support}(D) subseteq B_R$ where $B_R$ is the Euclidean ball of radius $R$ centered at the origin. The inequality written in your question is equivalent: it simply states that all elements in the set $text{support}(D)$ have Euclidean norm $le R$.



          Long story short, the assumption is saying that the distribution $D$ gives zero probability to subsets lying outside of the Euclidean ball of radius $R$.






          share|cite|improve this answer









          $endgroup$













          • $begingroup$
            Thank you so much. It was very intuitive, specially the conclusion. Is this assumption something as we assume the norm of decision variable is less than $M$ in optimization?
            $endgroup$
            – Saeed
            Dec 27 '18 at 1:00
















          1












          $begingroup$

          Roughly speaking, the support of a distribution is a closed set that contains [as subsets] all the sets with positive probability. For example, the uniform distribution on $[0,1]$ has support $[0,1]$, the exponential distribution has support $[0, infty)$, and the Gaussian distribution has support $mathbb{R}$. See the Wikipedia link for a more rigorous definition.



          So $text{support}(D)$ is a set, and the statement is simply saying $text{support}(D) subseteq B_R$ where $B_R$ is the Euclidean ball of radius $R$ centered at the origin. The inequality written in your question is equivalent: it simply states that all elements in the set $text{support}(D)$ have Euclidean norm $le R$.



          Long story short, the assumption is saying that the distribution $D$ gives zero probability to subsets lying outside of the Euclidean ball of radius $R$.






          share|cite|improve this answer









          $endgroup$













          • $begingroup$
            Thank you so much. It was very intuitive, specially the conclusion. Is this assumption something as we assume the norm of decision variable is less than $M$ in optimization?
            $endgroup$
            – Saeed
            Dec 27 '18 at 1:00














          1












          1








          1





          $begingroup$

          Roughly speaking, the support of a distribution is a closed set that contains [as subsets] all the sets with positive probability. For example, the uniform distribution on $[0,1]$ has support $[0,1]$, the exponential distribution has support $[0, infty)$, and the Gaussian distribution has support $mathbb{R}$. See the Wikipedia link for a more rigorous definition.



          So $text{support}(D)$ is a set, and the statement is simply saying $text{support}(D) subseteq B_R$ where $B_R$ is the Euclidean ball of radius $R$ centered at the origin. The inequality written in your question is equivalent: it simply states that all elements in the set $text{support}(D)$ have Euclidean norm $le R$.



          Long story short, the assumption is saying that the distribution $D$ gives zero probability to subsets lying outside of the Euclidean ball of radius $R$.






          share|cite|improve this answer









          $endgroup$



          Roughly speaking, the support of a distribution is a closed set that contains [as subsets] all the sets with positive probability. For example, the uniform distribution on $[0,1]$ has support $[0,1]$, the exponential distribution has support $[0, infty)$, and the Gaussian distribution has support $mathbb{R}$. See the Wikipedia link for a more rigorous definition.



          So $text{support}(D)$ is a set, and the statement is simply saying $text{support}(D) subseteq B_R$ where $B_R$ is the Euclidean ball of radius $R$ centered at the origin. The inequality written in your question is equivalent: it simply states that all elements in the set $text{support}(D)$ have Euclidean norm $le R$.



          Long story short, the assumption is saying that the distribution $D$ gives zero probability to subsets lying outside of the Euclidean ball of radius $R$.







          share|cite|improve this answer












          share|cite|improve this answer



          share|cite|improve this answer










          answered Dec 27 '18 at 0:45









          angryavianangryavian

          41.1k23380




          41.1k23380












          • $begingroup$
            Thank you so much. It was very intuitive, specially the conclusion. Is this assumption something as we assume the norm of decision variable is less than $M$ in optimization?
            $endgroup$
            – Saeed
            Dec 27 '18 at 1:00


















          • $begingroup$
            Thank you so much. It was very intuitive, specially the conclusion. Is this assumption something as we assume the norm of decision variable is less than $M$ in optimization?
            $endgroup$
            – Saeed
            Dec 27 '18 at 1:00
















          $begingroup$
          Thank you so much. It was very intuitive, specially the conclusion. Is this assumption something as we assume the norm of decision variable is less than $M$ in optimization?
          $endgroup$
          – Saeed
          Dec 27 '18 at 1:00




          $begingroup$
          Thank you so much. It was very intuitive, specially the conclusion. Is this assumption something as we assume the norm of decision variable is less than $M$ in optimization?
          $endgroup$
          – Saeed
          Dec 27 '18 at 1:00


















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