Operator raised to the power of another operator

The name of the pictureThe name of the pictureThe name of the pictureClash Royale CLAN TAG#URR8PPP











up vote
0
down vote

favorite












I was reading a paper and encountered the following notation:



Let $mathcalH=ell^2(mathbbZ)$ and $e_p_pin mathbbZ$ be an orthonormal basis of $mathcalH$.Define
$$ue_p=e_p+1quad andquad hatNe_p=pe_p$$
and define the operator
$$W=(1otimes u)^hatNotimes 1=int_mathbbZtimesmathbbTz^sdE_hatN(s)otimes dE_u(z)$$
$$e_kotimes e_lmapsto e_kotimes e_l+k$$ where $dE_hatN$ and $dE_u$ are the spectral measures of $hatN$ and $u$, respectively.



I know how to integrate with respect to a single measure or with respect to product measures. But here, the integration is with respect to tensor product of measures. I am confused whether $int f(x,y)d(muotimesnu)$ and $int f(x,y)dmuotimes dnu$ are equal or they are completely tow different things. I guess they are not equal.



Can anyone please elaborate what is going on in the definition of $W$ and how to calculate this type of integrals? or are there any other sense in which one can give meaning to an operator raised to the power of another operator? Any good reference in this direction would be highly appreciated.



Thanx in advance.







share|cite|improve this question
























    up vote
    0
    down vote

    favorite












    I was reading a paper and encountered the following notation:



    Let $mathcalH=ell^2(mathbbZ)$ and $e_p_pin mathbbZ$ be an orthonormal basis of $mathcalH$.Define
    $$ue_p=e_p+1quad andquad hatNe_p=pe_p$$
    and define the operator
    $$W=(1otimes u)^hatNotimes 1=int_mathbbZtimesmathbbTz^sdE_hatN(s)otimes dE_u(z)$$
    $$e_kotimes e_lmapsto e_kotimes e_l+k$$ where $dE_hatN$ and $dE_u$ are the spectral measures of $hatN$ and $u$, respectively.



    I know how to integrate with respect to a single measure or with respect to product measures. But here, the integration is with respect to tensor product of measures. I am confused whether $int f(x,y)d(muotimesnu)$ and $int f(x,y)dmuotimes dnu$ are equal or they are completely tow different things. I guess they are not equal.



    Can anyone please elaborate what is going on in the definition of $W$ and how to calculate this type of integrals? or are there any other sense in which one can give meaning to an operator raised to the power of another operator? Any good reference in this direction would be highly appreciated.



    Thanx in advance.







    share|cite|improve this question






















      up vote
      0
      down vote

      favorite









      up vote
      0
      down vote

      favorite











      I was reading a paper and encountered the following notation:



      Let $mathcalH=ell^2(mathbbZ)$ and $e_p_pin mathbbZ$ be an orthonormal basis of $mathcalH$.Define
      $$ue_p=e_p+1quad andquad hatNe_p=pe_p$$
      and define the operator
      $$W=(1otimes u)^hatNotimes 1=int_mathbbZtimesmathbbTz^sdE_hatN(s)otimes dE_u(z)$$
      $$e_kotimes e_lmapsto e_kotimes e_l+k$$ where $dE_hatN$ and $dE_u$ are the spectral measures of $hatN$ and $u$, respectively.



      I know how to integrate with respect to a single measure or with respect to product measures. But here, the integration is with respect to tensor product of measures. I am confused whether $int f(x,y)d(muotimesnu)$ and $int f(x,y)dmuotimes dnu$ are equal or they are completely tow different things. I guess they are not equal.



      Can anyone please elaborate what is going on in the definition of $W$ and how to calculate this type of integrals? or are there any other sense in which one can give meaning to an operator raised to the power of another operator? Any good reference in this direction would be highly appreciated.



      Thanx in advance.







      share|cite|improve this question












      I was reading a paper and encountered the following notation:



      Let $mathcalH=ell^2(mathbbZ)$ and $e_p_pin mathbbZ$ be an orthonormal basis of $mathcalH$.Define
      $$ue_p=e_p+1quad andquad hatNe_p=pe_p$$
      and define the operator
      $$W=(1otimes u)^hatNotimes 1=int_mathbbZtimesmathbbTz^sdE_hatN(s)otimes dE_u(z)$$
      $$e_kotimes e_lmapsto e_kotimes e_l+k$$ where $dE_hatN$ and $dE_u$ are the spectral measures of $hatN$ and $u$, respectively.



      I know how to integrate with respect to a single measure or with respect to product measures. But here, the integration is with respect to tensor product of measures. I am confused whether $int f(x,y)d(muotimesnu)$ and $int f(x,y)dmuotimes dnu$ are equal or they are completely tow different things. I guess they are not equal.



      Can anyone please elaborate what is going on in the definition of $W$ and how to calculate this type of integrals? or are there any other sense in which one can give meaning to an operator raised to the power of another operator? Any good reference in this direction would be highly appreciated.



      Thanx in advance.









      share|cite|improve this question











      share|cite|improve this question




      share|cite|improve this question










      asked Aug 12 at 6:57









      Dastan

      818




      818

























          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: false,
          showLowRepImageUploadWarning: true,
          reputationToPostImages: 10,
          bindNavPrevention: true,
          postfix: "",
          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%2f2880052%2foperator-raised-to-the-power-of-another-operator%23new-answer', 'question_page');

          );

          Post as a guest



































          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%2f2880052%2foperator-raised-to-the-power-of-another-operator%23new-answer', 'question_page');

          );

          Post as a guest













































































          這個網誌中的熱門文章

          How to combine Bézier curves to a surface?

          Carbon dioxide

          Why am i infinitely getting the same tweet with the Twitter Search API?