exercise:12796432f4: Difference between revisions

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(Created page with "<div class="d-none"><math> \newcommand{\NA}{{\rm NA}} \newcommand{\mat}[1]{{\bf#1}} \newcommand{\exref}[1]{\ref{##1}} \newcommand{\secstoprocess}{\all} \newcommand{\NA}{{\rm NA}} \newcommand{\mathds}{\mathbb}</math></div> Let <math>X</math> denote a particular process that produces elements of <math>S_n</math>, and let <math>U</math> denote the uniform process. Let the distribution functions of these processes be denoted by <math>f_X</math> and <math>u</math>, res...")
 
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<div class="d-none"><math>
Let <math>X</math> denote a particular process that produces elements of <math>S_n</math>, and let <math>U</math> denote the uniform process.  Let the distribution functions of these processes be denoted by <math>f_X</math> and <math>u</math>, respectively.  Show that the variation
\newcommand{\NA}{{\rm NA}}
\newcommand{\mat}[1]{{\bf#1}}
\newcommand{\exref}[1]{\ref{##1}}
\newcommand{\secstoprocess}{\all}
\newcommand{\NA}{{\rm NA}}
\newcommand{\mathds}{\mathbb}</math></div> Let <math>X</math> denote a particular process that produces elements of
<math>S_n</math>, and let <math>U</math> denote the uniform process.  Let the distribution functions of
these processes be denoted by <math>f_X</math> and <math>u</math>, respectively.  Show that the variation
distance  
distance  
\newline
 
<math>\parallel f_X - u\parallel</math> is equal to  
<math>\parallel f_X - u\parallel</math> is equal to  


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</math>
</math>


'' Hint'':  
''Hint'': Write the permutations in <math>S_n</math> in decreasing order of the difference <math>f_X(\pi) -
Write the permutations in <math>S_n</math> in decreasing order of the difference <math>f_X(\pi) -
u(\pi)</math>.
u(\pi)</math>.

Latest revision as of 23:30, 12 June 2024

Let [math]X[/math] denote a particular process that produces elements of [math]S_n[/math], and let [math]U[/math] denote the uniform process. Let the distribution functions of these processes be denoted by [math]f_X[/math] and [math]u[/math], respectively. Show that the variation distance

[math]\parallel f_X - u\parallel[/math] is equal to

[[math]] \max_{T \subset S_n} \sum_{\pi \in T} \Bigl(f_X(\pi) - u(\pi)\Bigr)\ . [[/math]]

Hint: Write the permutations in [math]S_n[/math] in decreasing order of the difference [math]f_X(\pi) - u(\pi)[/math].