Can a tree graph have only one vertex? And if so, that means that a tree graph has at minimum one leaf?












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Also, if the tree is two vertices connected by an edge, does the root count as a leaf too? Since it's also a vertex of degree one?



I've had trouble clarifying this online and from my textbook. Thank you.










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    0












    $begingroup$


    Also, if the tree is two vertices connected by an edge, does the root count as a leaf too? Since it's also a vertex of degree one?



    I've had trouble clarifying this online and from my textbook. Thank you.










    share|cite|improve this question











    $endgroup$















      0












      0








      0





      $begingroup$


      Also, if the tree is two vertices connected by an edge, does the root count as a leaf too? Since it's also a vertex of degree one?



      I've had trouble clarifying this online and from my textbook. Thank you.










      share|cite|improve this question











      $endgroup$




      Also, if the tree is two vertices connected by an edge, does the root count as a leaf too? Since it's also a vertex of degree one?



      I've had trouble clarifying this online and from my textbook. Thank you.







      discrete-mathematics trees






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      share|cite|improve this question













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      edited Dec 16 '18 at 20:34







      JLotus

















      asked Dec 16 '18 at 20:24









      JLotusJLotus

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          For the former: yes, by most definitions, the one-vertex, zero-edge graph is a tree.



          For the latter: No. For example, the infinite 2-regular tree has no leaves.






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          • $begingroup$
            Ok thank you. My teacher wrote in her notes that it has at minimum one leaf and then wrote that it has two minimum elsewhere. Perhaps she meant to say one leaf minimum for our purposes.
            $endgroup$
            – JLotus
            Dec 16 '18 at 20:32











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          1 Answer
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          0












          $begingroup$

          For the former: yes, by most definitions, the one-vertex, zero-edge graph is a tree.



          For the latter: No. For example, the infinite 2-regular tree has no leaves.






          share|cite|improve this answer









          $endgroup$













          • $begingroup$
            Ok thank you. My teacher wrote in her notes that it has at minimum one leaf and then wrote that it has two minimum elsewhere. Perhaps she meant to say one leaf minimum for our purposes.
            $endgroup$
            – JLotus
            Dec 16 '18 at 20:32
















          0












          $begingroup$

          For the former: yes, by most definitions, the one-vertex, zero-edge graph is a tree.



          For the latter: No. For example, the infinite 2-regular tree has no leaves.






          share|cite|improve this answer









          $endgroup$













          • $begingroup$
            Ok thank you. My teacher wrote in her notes that it has at minimum one leaf and then wrote that it has two minimum elsewhere. Perhaps she meant to say one leaf minimum for our purposes.
            $endgroup$
            – JLotus
            Dec 16 '18 at 20:32














          0












          0








          0





          $begingroup$

          For the former: yes, by most definitions, the one-vertex, zero-edge graph is a tree.



          For the latter: No. For example, the infinite 2-regular tree has no leaves.






          share|cite|improve this answer









          $endgroup$



          For the former: yes, by most definitions, the one-vertex, zero-edge graph is a tree.



          For the latter: No. For example, the infinite 2-regular tree has no leaves.







          share|cite|improve this answer












          share|cite|improve this answer



          share|cite|improve this answer










          answered Dec 16 '18 at 20:28









          user3482749user3482749

          3,952418




          3,952418












          • $begingroup$
            Ok thank you. My teacher wrote in her notes that it has at minimum one leaf and then wrote that it has two minimum elsewhere. Perhaps she meant to say one leaf minimum for our purposes.
            $endgroup$
            – JLotus
            Dec 16 '18 at 20:32


















          • $begingroup$
            Ok thank you. My teacher wrote in her notes that it has at minimum one leaf and then wrote that it has two minimum elsewhere. Perhaps she meant to say one leaf minimum for our purposes.
            $endgroup$
            – JLotus
            Dec 16 '18 at 20:32
















          $begingroup$
          Ok thank you. My teacher wrote in her notes that it has at minimum one leaf and then wrote that it has two minimum elsewhere. Perhaps she meant to say one leaf minimum for our purposes.
          $endgroup$
          – JLotus
          Dec 16 '18 at 20:32




          $begingroup$
          Ok thank you. My teacher wrote in her notes that it has at minimum one leaf and then wrote that it has two minimum elsewhere. Perhaps she meant to say one leaf minimum for our purposes.
          $endgroup$
          – JLotus
          Dec 16 '18 at 20:32


















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