$L^p$ integrability question












1












$begingroup$


The question is simply: If I have two random variables $X,Y in bigcap_{pgeq 1} L^p(Omega)$ and a third $Z$ r.v. such that
$$XZ=Y$$
can I conclude that $Zin bigcap_{pgeq 1}L^p(Omega)$?
(I know this would't hold for a single $L^p(Omega)$ space, the point is that both $X$ and $Y$ are in all $L^p(Omega)$, $pgeq 1$)



Or, in other words, if $Xneq 0$, $Xin bigcap_{pgeq 1} L^p(Omega)$ is then $1/X in bigcap_{pgeq 1} L^p(Omega)$?



Thank you very much for the help!










share|cite|improve this question











$endgroup$

















    1












    $begingroup$


    The question is simply: If I have two random variables $X,Y in bigcap_{pgeq 1} L^p(Omega)$ and a third $Z$ r.v. such that
    $$XZ=Y$$
    can I conclude that $Zin bigcap_{pgeq 1}L^p(Omega)$?
    (I know this would't hold for a single $L^p(Omega)$ space, the point is that both $X$ and $Y$ are in all $L^p(Omega)$, $pgeq 1$)



    Or, in other words, if $Xneq 0$, $Xin bigcap_{pgeq 1} L^p(Omega)$ is then $1/X in bigcap_{pgeq 1} L^p(Omega)$?



    Thank you very much for the help!










    share|cite|improve this question











    $endgroup$















      1












      1








      1





      $begingroup$


      The question is simply: If I have two random variables $X,Y in bigcap_{pgeq 1} L^p(Omega)$ and a third $Z$ r.v. such that
      $$XZ=Y$$
      can I conclude that $Zin bigcap_{pgeq 1}L^p(Omega)$?
      (I know this would't hold for a single $L^p(Omega)$ space, the point is that both $X$ and $Y$ are in all $L^p(Omega)$, $pgeq 1$)



      Or, in other words, if $Xneq 0$, $Xin bigcap_{pgeq 1} L^p(Omega)$ is then $1/X in bigcap_{pgeq 1} L^p(Omega)$?



      Thank you very much for the help!










      share|cite|improve this question











      $endgroup$




      The question is simply: If I have two random variables $X,Y in bigcap_{pgeq 1} L^p(Omega)$ and a third $Z$ r.v. such that
      $$XZ=Y$$
      can I conclude that $Zin bigcap_{pgeq 1}L^p(Omega)$?
      (I know this would't hold for a single $L^p(Omega)$ space, the point is that both $X$ and $Y$ are in all $L^p(Omega)$, $pgeq 1$)



      Or, in other words, if $Xneq 0$, $Xin bigcap_{pgeq 1} L^p(Omega)$ is then $1/X in bigcap_{pgeq 1} L^p(Omega)$?



      Thank you very much for the help!







      real-analysis probability-theory measure-theory random-variables lp-spaces






      share|cite|improve this question















      share|cite|improve this question













      share|cite|improve this question




      share|cite|improve this question








      edited Dec 7 '18 at 13:47









      Davide Giraudo

      126k16150261




      126k16150261










      asked Aug 15 '13 at 13:29









      MarkMark

      82




      82






















          1 Answer
          1






          active

          oldest

          votes


















          1












          $begingroup$

          Take $Omega:=(0,1)$ with Lebesgue measure and $X(omega):=omega$. $X$ is bounded, hence in all the $L^p$ (as $Omega$ has finite measure) but its reciprocal is not even integrable.






          share|cite|improve this answer











          $endgroup$













            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%2f468267%2flp-integrability-question%23new-answer', 'question_page');
            }
            );

            Post as a guest















            Required, but never shown

























            1 Answer
            1






            active

            oldest

            votes








            1 Answer
            1






            active

            oldest

            votes









            active

            oldest

            votes






            active

            oldest

            votes









            1












            $begingroup$

            Take $Omega:=(0,1)$ with Lebesgue measure and $X(omega):=omega$. $X$ is bounded, hence in all the $L^p$ (as $Omega$ has finite measure) but its reciprocal is not even integrable.






            share|cite|improve this answer











            $endgroup$


















              1












              $begingroup$

              Take $Omega:=(0,1)$ with Lebesgue measure and $X(omega):=omega$. $X$ is bounded, hence in all the $L^p$ (as $Omega$ has finite measure) but its reciprocal is not even integrable.






              share|cite|improve this answer











              $endgroup$
















                1












                1








                1





                $begingroup$

                Take $Omega:=(0,1)$ with Lebesgue measure and $X(omega):=omega$. $X$ is bounded, hence in all the $L^p$ (as $Omega$ has finite measure) but its reciprocal is not even integrable.






                share|cite|improve this answer











                $endgroup$



                Take $Omega:=(0,1)$ with Lebesgue measure and $X(omega):=omega$. $X$ is bounded, hence in all the $L^p$ (as $Omega$ has finite measure) but its reciprocal is not even integrable.







                share|cite|improve this answer














                share|cite|improve this answer



                share|cite|improve this answer








                edited Dec 7 '18 at 5:53









                Drew Brady

                712315




                712315










                answered Aug 15 '13 at 13:55









                Davide GiraudoDavide Giraudo

                126k16150261




                126k16150261






























                    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.




                    draft saved


                    draft discarded














                    StackExchange.ready(
                    function () {
                    StackExchange.openid.initPostLogin('.new-post-login', 'https%3a%2f%2fmath.stackexchange.com%2fquestions%2f468267%2flp-integrability-question%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