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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?













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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






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      asked 28 mins ago









      lthompsonlthompson

      1169




      1169






















          2 Answers
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          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









            $endgroup$













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              2 Answers
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              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 22 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 22 mins ago









                          Ross MillikanRoss Millikan

                          298k24200373




                          298k24200373






























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