Monotone eigenvector











up vote
0
down vote

favorite












Definition: We say that a vector $xinmathbb{R}^n$ is monotone if, $x_1geq x_2 geq cdots geq x_n$ or $x_1 leq x_2 leq cdots leq x_n$.



Let $M=(m_{ij})_{1leq i,j leq n}$ be a matrix defined by $m_{ij}=1$ if $|i-j|leq frac{n}{2}$ and $m_{ij}=0$ otherwise. Show that the eigenvector corresponding to the second largest eigenvalue is monotone. (i.e., if $lambda_1geqlambda_2cdotsgeqlambda_n$ are the eigenvalues in non-increasing order and $v_1,v_2,ldots,v_n$ are the corresponding eigenvectors then $v_2$ is monotone).



We can prove this by finding a closed-form expression of the eigenvector, but I am trying to figure out if there is an other way, in fact one can show the same for the matrix defined by $m_{ij}=n-|i-j|$. Note that both are Toeplitz matrices, and Robinsonian matrices!



In this article the authors show that : if $M$ is a Robinsonian matrix and $L_M$ is the corresponding Laplacian, then the eigenvector corresponding to the second smallest eigenvalue (called the Fiedler vector) is monotone. I am wondering if there is a link?










share|cite|improve this question


























    up vote
    0
    down vote

    favorite












    Definition: We say that a vector $xinmathbb{R}^n$ is monotone if, $x_1geq x_2 geq cdots geq x_n$ or $x_1 leq x_2 leq cdots leq x_n$.



    Let $M=(m_{ij})_{1leq i,j leq n}$ be a matrix defined by $m_{ij}=1$ if $|i-j|leq frac{n}{2}$ and $m_{ij}=0$ otherwise. Show that the eigenvector corresponding to the second largest eigenvalue is monotone. (i.e., if $lambda_1geqlambda_2cdotsgeqlambda_n$ are the eigenvalues in non-increasing order and $v_1,v_2,ldots,v_n$ are the corresponding eigenvectors then $v_2$ is monotone).



    We can prove this by finding a closed-form expression of the eigenvector, but I am trying to figure out if there is an other way, in fact one can show the same for the matrix defined by $m_{ij}=n-|i-j|$. Note that both are Toeplitz matrices, and Robinsonian matrices!



    In this article the authors show that : if $M$ is a Robinsonian matrix and $L_M$ is the corresponding Laplacian, then the eigenvector corresponding to the second smallest eigenvalue (called the Fiedler vector) is monotone. I am wondering if there is a link?










    share|cite|improve this question
























      up vote
      0
      down vote

      favorite









      up vote
      0
      down vote

      favorite











      Definition: We say that a vector $xinmathbb{R}^n$ is monotone if, $x_1geq x_2 geq cdots geq x_n$ or $x_1 leq x_2 leq cdots leq x_n$.



      Let $M=(m_{ij})_{1leq i,j leq n}$ be a matrix defined by $m_{ij}=1$ if $|i-j|leq frac{n}{2}$ and $m_{ij}=0$ otherwise. Show that the eigenvector corresponding to the second largest eigenvalue is monotone. (i.e., if $lambda_1geqlambda_2cdotsgeqlambda_n$ are the eigenvalues in non-increasing order and $v_1,v_2,ldots,v_n$ are the corresponding eigenvectors then $v_2$ is monotone).



      We can prove this by finding a closed-form expression of the eigenvector, but I am trying to figure out if there is an other way, in fact one can show the same for the matrix defined by $m_{ij}=n-|i-j|$. Note that both are Toeplitz matrices, and Robinsonian matrices!



      In this article the authors show that : if $M$ is a Robinsonian matrix and $L_M$ is the corresponding Laplacian, then the eigenvector corresponding to the second smallest eigenvalue (called the Fiedler vector) is monotone. I am wondering if there is a link?










      share|cite|improve this question













      Definition: We say that a vector $xinmathbb{R}^n$ is monotone if, $x_1geq x_2 geq cdots geq x_n$ or $x_1 leq x_2 leq cdots leq x_n$.



      Let $M=(m_{ij})_{1leq i,j leq n}$ be a matrix defined by $m_{ij}=1$ if $|i-j|leq frac{n}{2}$ and $m_{ij}=0$ otherwise. Show that the eigenvector corresponding to the second largest eigenvalue is monotone. (i.e., if $lambda_1geqlambda_2cdotsgeqlambda_n$ are the eigenvalues in non-increasing order and $v_1,v_2,ldots,v_n$ are the corresponding eigenvectors then $v_2$ is monotone).



      We can prove this by finding a closed-form expression of the eigenvector, but I am trying to figure out if there is an other way, in fact one can show the same for the matrix defined by $m_{ij}=n-|i-j|$. Note that both are Toeplitz matrices, and Robinsonian matrices!



      In this article the authors show that : if $M$ is a Robinsonian matrix and $L_M$ is the corresponding Laplacian, then the eigenvector corresponding to the second smallest eigenvalue (called the Fiedler vector) is monotone. I am wondering if there is a link?







      linear-algebra graph-theory eigenvalues-eigenvectors laplacian graph-laplacian






      share|cite|improve this question













      share|cite|improve this question











      share|cite|improve this question




      share|cite|improve this question










      asked yesterday









      Samovem

      91




      91



























          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',
          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%2f3004957%2fmonotone-eigenvector%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



















































           


          draft saved


          draft discarded














          StackExchange.ready(
          function () {
          StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fmath.stackexchange.com%2fquestions%2f3004957%2fmonotone-eigenvector%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

          android studio warns about leanback feature tag usage required on manifest while using Unity exported app?

          SQL update select statement

          'app-layout' is not a known element: how to share Component with different Modules