Does bilinear models on vectors mean dot or outer product?












0












$begingroup$


If I have 2 vectors $x$ and $y$ where $x in mathcal{R}^{m}$ and $y in mathcal{R}^{n}$.

Does bilinear model mean?
$f(x,y) = x^TWy$ where $W in mathcal{R}^{m*n}$
which result in a scalar

or
$f(x,y) = W(x⊗y^T)$ where ⊗ is the outer
product and $W in mathcal{R}^{m*n}$.
which result in a matrix



I checked 2 papers, the first one Low-rank Bilinear Pooling
in page 2 in equation 1 their bilinear model produce a scalar

while in Compact Bilinear Pooling in section 3.1 they said "Bilinear models take the outer product of two vectors"










share|cite|improve this question









$endgroup$

















    0












    $begingroup$


    If I have 2 vectors $x$ and $y$ where $x in mathcal{R}^{m}$ and $y in mathcal{R}^{n}$.

    Does bilinear model mean?
    $f(x,y) = x^TWy$ where $W in mathcal{R}^{m*n}$
    which result in a scalar

    or
    $f(x,y) = W(x⊗y^T)$ where ⊗ is the outer
    product and $W in mathcal{R}^{m*n}$.
    which result in a matrix



    I checked 2 papers, the first one Low-rank Bilinear Pooling
    in page 2 in equation 1 their bilinear model produce a scalar

    while in Compact Bilinear Pooling in section 3.1 they said "Bilinear models take the outer product of two vectors"










    share|cite|improve this question









    $endgroup$















      0












      0








      0





      $begingroup$


      If I have 2 vectors $x$ and $y$ where $x in mathcal{R}^{m}$ and $y in mathcal{R}^{n}$.

      Does bilinear model mean?
      $f(x,y) = x^TWy$ where $W in mathcal{R}^{m*n}$
      which result in a scalar

      or
      $f(x,y) = W(x⊗y^T)$ where ⊗ is the outer
      product and $W in mathcal{R}^{m*n}$.
      which result in a matrix



      I checked 2 papers, the first one Low-rank Bilinear Pooling
      in page 2 in equation 1 their bilinear model produce a scalar

      while in Compact Bilinear Pooling in section 3.1 they said "Bilinear models take the outer product of two vectors"










      share|cite|improve this question









      $endgroup$




      If I have 2 vectors $x$ and $y$ where $x in mathcal{R}^{m}$ and $y in mathcal{R}^{n}$.

      Does bilinear model mean?
      $f(x,y) = x^TWy$ where $W in mathcal{R}^{m*n}$
      which result in a scalar

      or
      $f(x,y) = W(x⊗y^T)$ where ⊗ is the outer
      product and $W in mathcal{R}^{m*n}$.
      which result in a matrix



      I checked 2 papers, the first one Low-rank Bilinear Pooling
      in page 2 in equation 1 their bilinear model produce a scalar

      while in Compact Bilinear Pooling in section 3.1 they said "Bilinear models take the outer product of two vectors"







      linear-algebra matrices






      share|cite|improve this question













      share|cite|improve this question











      share|cite|improve this question




      share|cite|improve this question










      asked Dec 19 '18 at 11:53









      floydfloyd

      1032




      1032






















          1 Answer
          1






          active

          oldest

          votes


















          1












          $begingroup$

          "Bilinear" is simply an adjective that you can apply to any function of two vectors to indicate that it is linear in each argument. So the linear map



          $(x,y) rightarrow x^TWy$



          and the tensor product



          $(x,y) rightarrow xy^T$



          can both be described as bilinear, even though their codomains are different.






          share|cite|improve this answer









          $endgroup$













          • $begingroup$
            What about the element-wise product between 2 vectors? The reason I mention it is because it's different than the dot and outer product because it's doesn't take into account all the interactions between the 2 vectors (like what the dot product does).
            $endgroup$
            – floyd
            Jan 7 at 20:20












          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%2f3046295%2fdoes-bilinear-models-on-vectors-mean-dot-or-outer-product%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












          $begingroup$

          "Bilinear" is simply an adjective that you can apply to any function of two vectors to indicate that it is linear in each argument. So the linear map



          $(x,y) rightarrow x^TWy$



          and the tensor product



          $(x,y) rightarrow xy^T$



          can both be described as bilinear, even though their codomains are different.






          share|cite|improve this answer









          $endgroup$













          • $begingroup$
            What about the element-wise product between 2 vectors? The reason I mention it is because it's different than the dot and outer product because it's doesn't take into account all the interactions between the 2 vectors (like what the dot product does).
            $endgroup$
            – floyd
            Jan 7 at 20:20
















          1












          $begingroup$

          "Bilinear" is simply an adjective that you can apply to any function of two vectors to indicate that it is linear in each argument. So the linear map



          $(x,y) rightarrow x^TWy$



          and the tensor product



          $(x,y) rightarrow xy^T$



          can both be described as bilinear, even though their codomains are different.






          share|cite|improve this answer









          $endgroup$













          • $begingroup$
            What about the element-wise product between 2 vectors? The reason I mention it is because it's different than the dot and outer product because it's doesn't take into account all the interactions between the 2 vectors (like what the dot product does).
            $endgroup$
            – floyd
            Jan 7 at 20:20














          1












          1








          1





          $begingroup$

          "Bilinear" is simply an adjective that you can apply to any function of two vectors to indicate that it is linear in each argument. So the linear map



          $(x,y) rightarrow x^TWy$



          and the tensor product



          $(x,y) rightarrow xy^T$



          can both be described as bilinear, even though their codomains are different.






          share|cite|improve this answer









          $endgroup$



          "Bilinear" is simply an adjective that you can apply to any function of two vectors to indicate that it is linear in each argument. So the linear map



          $(x,y) rightarrow x^TWy$



          and the tensor product



          $(x,y) rightarrow xy^T$



          can both be described as bilinear, even though their codomains are different.







          share|cite|improve this answer












          share|cite|improve this answer



          share|cite|improve this answer










          answered Dec 19 '18 at 12:16









          gandalf61gandalf61

          9,199825




          9,199825












          • $begingroup$
            What about the element-wise product between 2 vectors? The reason I mention it is because it's different than the dot and outer product because it's doesn't take into account all the interactions between the 2 vectors (like what the dot product does).
            $endgroup$
            – floyd
            Jan 7 at 20:20


















          • $begingroup$
            What about the element-wise product between 2 vectors? The reason I mention it is because it's different than the dot and outer product because it's doesn't take into account all the interactions between the 2 vectors (like what the dot product does).
            $endgroup$
            – floyd
            Jan 7 at 20:20
















          $begingroup$
          What about the element-wise product between 2 vectors? The reason I mention it is because it's different than the dot and outer product because it's doesn't take into account all the interactions between the 2 vectors (like what the dot product does).
          $endgroup$
          – floyd
          Jan 7 at 20:20




          $begingroup$
          What about the element-wise product between 2 vectors? The reason I mention it is because it's different than the dot and outer product because it's doesn't take into account all the interactions between the 2 vectors (like what the dot product does).
          $endgroup$
          – floyd
          Jan 7 at 20:20


















          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%2f3046295%2fdoes-bilinear-models-on-vectors-mean-dot-or-outer-product%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

          Plaza Victoria

          In PowerPoint, is there a keyboard shortcut for bulleted / numbered list?

          How to put 3 figures in Latex with 2 figures side by side and 1 below these side by side images but in...