How to derive the optimal bayesian solution to a model of two normal distributed populations












0














In the "Introduction" section of the paper Support-Vector Networks, it mentioned Fisher's solution to a model of two normal distributed populations:



Fisher's solution to a model of two normal distributed populations



My questions are:




  1. How to derive equation (1)? I even doubt that it should be:
    $F_{sq} (x) = sign left [ left ( x - m_1 right ) ^T Sigma_1 ^{-1} left ( x - m_1 right ) - left ( x - m_2 right ) ^T Sigma_2 ^{-1} left ( x - m_2 right ) + ln { dfrac { left | Sigma_1 right |} { left | Sigma_2 right | } } right ]$

    because according to Linear discriminant analysis, the solution is:
    Linear discriminant analysis


  2. Why the number of free parameters in equation (1) is $dfrac {n (n + 3)} {2}$?

    In my opinion, $m_1, m_2, Sigma_1, Sigma_2$ are all free parameters, because
    $Sigma_1, Sigma_2$ are symmetric matrices, so the number should be $n + n + dfrac {n left (n + 1 right )}{2} + dfrac {n left (n + 1 right )}{2} = n left (n + 3 right )$


  3. Why the number of free parameters in equation (2) is $n$?

    We can rewrite Equation (2) as $F_{sq} left ( X right ) = WX + b$, so $W$ and $b$ are both free parameters, then the number should be $n + 1$.











share|cite|improve this question



























    0














    In the "Introduction" section of the paper Support-Vector Networks, it mentioned Fisher's solution to a model of two normal distributed populations:



    Fisher's solution to a model of two normal distributed populations



    My questions are:




    1. How to derive equation (1)? I even doubt that it should be:
      $F_{sq} (x) = sign left [ left ( x - m_1 right ) ^T Sigma_1 ^{-1} left ( x - m_1 right ) - left ( x - m_2 right ) ^T Sigma_2 ^{-1} left ( x - m_2 right ) + ln { dfrac { left | Sigma_1 right |} { left | Sigma_2 right | } } right ]$

      because according to Linear discriminant analysis, the solution is:
      Linear discriminant analysis


    2. Why the number of free parameters in equation (1) is $dfrac {n (n + 3)} {2}$?

      In my opinion, $m_1, m_2, Sigma_1, Sigma_2$ are all free parameters, because
      $Sigma_1, Sigma_2$ are symmetric matrices, so the number should be $n + n + dfrac {n left (n + 1 right )}{2} + dfrac {n left (n + 1 right )}{2} = n left (n + 3 right )$


    3. Why the number of free parameters in equation (2) is $n$?

      We can rewrite Equation (2) as $F_{sq} left ( X right ) = WX + b$, so $W$ and $b$ are both free parameters, then the number should be $n + 1$.











    share|cite|improve this question

























      0












      0








      0







      In the "Introduction" section of the paper Support-Vector Networks, it mentioned Fisher's solution to a model of two normal distributed populations:



      Fisher's solution to a model of two normal distributed populations



      My questions are:




      1. How to derive equation (1)? I even doubt that it should be:
        $F_{sq} (x) = sign left [ left ( x - m_1 right ) ^T Sigma_1 ^{-1} left ( x - m_1 right ) - left ( x - m_2 right ) ^T Sigma_2 ^{-1} left ( x - m_2 right ) + ln { dfrac { left | Sigma_1 right |} { left | Sigma_2 right | } } right ]$

        because according to Linear discriminant analysis, the solution is:
        Linear discriminant analysis


      2. Why the number of free parameters in equation (1) is $dfrac {n (n + 3)} {2}$?

        In my opinion, $m_1, m_2, Sigma_1, Sigma_2$ are all free parameters, because
        $Sigma_1, Sigma_2$ are symmetric matrices, so the number should be $n + n + dfrac {n left (n + 1 right )}{2} + dfrac {n left (n + 1 right )}{2} = n left (n + 3 right )$


      3. Why the number of free parameters in equation (2) is $n$?

        We can rewrite Equation (2) as $F_{sq} left ( X right ) = WX + b$, so $W$ and $b$ are both free parameters, then the number should be $n + 1$.











      share|cite|improve this question













      In the "Introduction" section of the paper Support-Vector Networks, it mentioned Fisher's solution to a model of two normal distributed populations:



      Fisher's solution to a model of two normal distributed populations



      My questions are:




      1. How to derive equation (1)? I even doubt that it should be:
        $F_{sq} (x) = sign left [ left ( x - m_1 right ) ^T Sigma_1 ^{-1} left ( x - m_1 right ) - left ( x - m_2 right ) ^T Sigma_2 ^{-1} left ( x - m_2 right ) + ln { dfrac { left | Sigma_1 right |} { left | Sigma_2 right | } } right ]$

        because according to Linear discriminant analysis, the solution is:
        Linear discriminant analysis


      2. Why the number of free parameters in equation (1) is $dfrac {n (n + 3)} {2}$?

        In my opinion, $m_1, m_2, Sigma_1, Sigma_2$ are all free parameters, because
        $Sigma_1, Sigma_2$ are symmetric matrices, so the number should be $n + n + dfrac {n left (n + 1 right )}{2} + dfrac {n left (n + 1 right )}{2} = n left (n + 3 right )$


      3. Why the number of free parameters in equation (2) is $n$?

        We can rewrite Equation (2) as $F_{sq} left ( X right ) = WX + b$, so $W$ and $b$ are both free parameters, then the number should be $n + 1$.








      optimization bayesian fisher-information






      share|cite|improve this question













      share|cite|improve this question











      share|cite|improve this question




      share|cite|improve this question










      asked Nov 26 at 15:54









      Jiongjiong Li

      225




      225



























          active

          oldest

          votes











          Your Answer





          StackExchange.ifUsing("editor", function () {
          return StackExchange.using("mathjaxEditing", function () {
          StackExchange.MarkdownEditor.creationCallbacks.add(function (editor, postfix) {
          StackExchange.mathjaxEditing.prepareWmdForMathJax(editor, postfix, [["$", "$"], ["\\(","\\)"]]);
          });
          });
          }, "mathjax-editing");

          StackExchange.ready(function() {
          var channelOptions = {
          tags: "".split(" "),
          id: "69"
          };
          initTagRenderer("".split(" "), "".split(" "), channelOptions);

          StackExchange.using("externalEditor", function() {
          // Have to fire editor after snippets, if snippets enabled
          if (StackExchange.settings.snippets.snippetsEnabled) {
          StackExchange.using("snippets", function() {
          createEditor();
          });
          }
          else {
          createEditor();
          }
          });

          function createEditor() {
          StackExchange.prepareEditor({
          heartbeatType: 'answer',
          autoActivateHeartbeat: false,
          convertImagesToLinks: true,
          noModals: true,
          showLowRepImageUploadWarning: true,
          reputationToPostImages: 10,
          bindNavPrevention: true,
          postfix: "",
          imageUploader: {
          brandingHtml: "Powered by u003ca class="icon-imgur-white" href="https://imgur.com/"u003eu003c/au003e",
          contentPolicyHtml: "User contributions licensed under u003ca href="https://creativecommons.org/licenses/by-sa/3.0/"u003ecc by-sa 3.0 with attribution requiredu003c/au003e u003ca href="https://stackoverflow.com/legal/content-policy"u003e(content policy)u003c/au003e",
          allowUrls: true
          },
          noCode: true, onDemand: true,
          discardSelector: ".discard-answer"
          ,immediatelyShowMarkdownHelp:true
          });


          }
          });














          draft saved

          draft discarded


















          StackExchange.ready(
          function () {
          StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fmath.stackexchange.com%2fquestions%2f3014491%2fhow-to-derive-the-optimal-bayesian-solution-to-a-model-of-two-normal-distributed%23new-answer', 'question_page');
          }
          );

          Post as a guest















          Required, but never shown






























          active

          oldest

          votes













          active

          oldest

          votes









          active

          oldest

          votes






          active

          oldest

          votes
















          draft saved

          draft discarded




















































          Thanks for contributing an answer to Mathematics Stack Exchange!


          • Please be sure to answer the question. Provide details and share your research!

          But avoid



          • Asking for help, clarification, or responding to other answers.

          • Making statements based on opinion; back them up with references or personal experience.


          Use MathJax to format equations. MathJax reference.


          To learn more, see our tips on writing great answers.





          Some of your past answers have not been well-received, and you're in danger of being blocked from answering.


          Please pay close attention to the following guidance:


          • Please be sure to answer the question. Provide details and share your research!

          But avoid



          • Asking for help, clarification, or responding to other answers.

          • Making statements based on opinion; back them up with references or personal experience.


          To learn more, see our tips on writing great answers.




          draft saved


          draft discarded














          StackExchange.ready(
          function () {
          StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fmath.stackexchange.com%2fquestions%2f3014491%2fhow-to-derive-the-optimal-bayesian-solution-to-a-model-of-two-normal-distributed%23new-answer', 'question_page');
          }
          );

          Post as a guest















          Required, but never shown





















































          Required, but never shown














          Required, but never shown












          Required, but never shown







          Required, but never shown

































          Required, but never shown














          Required, but never shown












          Required, but never shown







          Required, but never shown







          Popular posts from this blog

          Ellipse (mathématiques)

          Quarter-circle Tiles

          Mont Emei