Every subset equal to original set?Is the void set (∅) a proper subset of every set?Set theory: difference...

Skis versus snow shoes - when to choose which for travelling the backcountry?

Are there any other Chaos-worshipping races?

VAT refund for a conference ticket in Sweden

Book about a time-travel war fought by computers

What happened to QGIS 2.x LTR?

Citing contemporaneous (interlaced?) preprints

Called into a meeting and told we are being made redundant (laid off) and "not to share outside". Can I tell my partner?

Wrap all numerics in JSON with quotes

How can I handle a player who pre-plans arguments about my rulings on RAW?

A bug in Excel? Conditional formatting for marking duplicates also highlights unique value

Reason why dimensional travelling would be restricted

Where is the fallacy here?

What are all the squawk codes?

What is better: yes / no radio, or simple checkbox?

Why can't we make a perpetual motion machine by using a magnet to pull up a piece of metal, then letting it fall back down?

Sometimes a banana is just a banana

Why do members of Congress in committee hearings ask witnesses the same question multiple times?

What could trigger powerful quakes on icy world?

Plagiarism of code by other PhD student

Every subset equal to original set?

Why do phishing e-mails use faked e-mail addresses instead of the real one?

Six real numbers so that product of any five is the sixth one

How to make a *empty* field behaves like a *null* field when it comes to standard values?

How to kill a localhost:8080



Every subset equal to original set?


Is the void set (∅) a proper subset of every set?Set theory: difference between belong/contained and includes/subset?Proving every infinite set is a subset of some denumerable set and vice versaIf the empty set is a subset of every set, why isn't ${emptyset,{a}}={{a}}$?What is the reason behind calling $emptyset$ improper subset of any non-empty set.?Can subset of a countable set be uncountable?Set Theory Subset QuestionIs every empty set equal?Why a set that is subset/equal to infinite set isn't infinite? (by definition)Why the empty set is a subset of every set?













1












$begingroup$


Is there any set whose every subset is equal to the set itself? It seems like this isn't possible, but maybe something similar is possible.










share|cite|improve this question









$endgroup$

















    1












    $begingroup$


    Is there any set whose every subset is equal to the set itself? It seems like this isn't possible, but maybe something similar is possible.










    share|cite|improve this question









    $endgroup$















      1












      1








      1





      $begingroup$


      Is there any set whose every subset is equal to the set itself? It seems like this isn't possible, but maybe something similar is possible.










      share|cite|improve this question









      $endgroup$




      Is there any set whose every subset is equal to the set itself? It seems like this isn't possible, but maybe something similar is possible.







      elementary-set-theory






      share|cite|improve this question













      share|cite|improve this question











      share|cite|improve this question




      share|cite|improve this question










      asked 39 mins ago









      lthompsonlthompson

      1169




      1169






















          2 Answers
          2






          active

          oldest

          votes


















          3












          $begingroup$

          In standard foundations (by which I mean ZF, or ZFC) the empty set works:
          If $Ssubset emptyset$, then $S = emptyset$.



          If you wish to do so otherwise, you’d violate the Axiom of Extensionality.






          share|cite|improve this answer









          $endgroup$





















            3












            $begingroup$

            The empty set has only itself as a subset. This is the only example because every set has the empty set as a subset.






            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%2f3137096%2fevery-subset-equal-to-original-set%23new-answer', 'question_page');
              }
              );

              Post as a guest















              Required, but never shown

























              2 Answers
              2






              active

              oldest

              votes








              2 Answers
              2






              active

              oldest

              votes









              active

              oldest

              votes






              active

              oldest

              votes









              3












              $begingroup$

              In standard foundations (by which I mean ZF, or ZFC) the empty set works:
              If $Ssubset emptyset$, then $S = emptyset$.



              If you wish to do so otherwise, you’d violate the Axiom of Extensionality.






              share|cite|improve this answer









              $endgroup$


















                3












                $begingroup$

                In standard foundations (by which I mean ZF, or ZFC) the empty set works:
                If $Ssubset emptyset$, then $S = emptyset$.



                If you wish to do so otherwise, you’d violate the Axiom of Extensionality.






                share|cite|improve this answer









                $endgroup$
















                  3












                  3








                  3





                  $begingroup$

                  In standard foundations (by which I mean ZF, or ZFC) the empty set works:
                  If $Ssubset emptyset$, then $S = emptyset$.



                  If you wish to do so otherwise, you’d violate the Axiom of Extensionality.






                  share|cite|improve this answer









                  $endgroup$



                  In standard foundations (by which I mean ZF, or ZFC) the empty set works:
                  If $Ssubset emptyset$, then $S = emptyset$.



                  If you wish to do so otherwise, you’d violate the Axiom of Extensionality.







                  share|cite|improve this answer












                  share|cite|improve this answer



                  share|cite|improve this answer










                  answered 33 mins ago









                  user458276user458276

                  743212




                  743212























                      3












                      $begingroup$

                      The empty set has only itself as a subset. This is the only example because every set has the empty set as a subset.






                      share|cite|improve this answer









                      $endgroup$


















                        3












                        $begingroup$

                        The empty set has only itself as a subset. This is the only example because every set has the empty set as a subset.






                        share|cite|improve this answer









                        $endgroup$
















                          3












                          3








                          3





                          $begingroup$

                          The empty set has only itself as a subset. This is the only example because every set has the empty set as a subset.






                          share|cite|improve this answer









                          $endgroup$



                          The empty set has only itself as a subset. This is the only example because every set has the empty set as a subset.







                          share|cite|improve this answer












                          share|cite|improve this answer



                          share|cite|improve this answer










                          answered 32 mins ago









                          Ross MillikanRoss Millikan

                          298k24200373




                          298k24200373






























                              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%2f3137096%2fevery-subset-equal-to-original-set%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