$2$-factorizations of a $4$-regular graph












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Suppose there is a $4$ regular graph. Then it has $2$ edge disjoint $2$-regular spanning subgraphs. Let the spanning subgraphs be $T_1$ and $T_2$. Can there be another pair $T_3$ and $T_4$ of edge disjoint $2$-regular spanning subgraphs for the same graph? I mean that can we regard the existance of two edge disjoint $2$-regular spanning subgraphs as a unique existance?










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    1












    $begingroup$


    Suppose there is a $4$ regular graph. Then it has $2$ edge disjoint $2$-regular spanning subgraphs. Let the spanning subgraphs be $T_1$ and $T_2$. Can there be another pair $T_3$ and $T_4$ of edge disjoint $2$-regular spanning subgraphs for the same graph? I mean that can we regard the existance of two edge disjoint $2$-regular spanning subgraphs as a unique existance?










    share|cite|improve this question











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      1












      1








      1





      $begingroup$


      Suppose there is a $4$ regular graph. Then it has $2$ edge disjoint $2$-regular spanning subgraphs. Let the spanning subgraphs be $T_1$ and $T_2$. Can there be another pair $T_3$ and $T_4$ of edge disjoint $2$-regular spanning subgraphs for the same graph? I mean that can we regard the existance of two edge disjoint $2$-regular spanning subgraphs as a unique existance?










      share|cite|improve this question











      $endgroup$




      Suppose there is a $4$ regular graph. Then it has $2$ edge disjoint $2$-regular spanning subgraphs. Let the spanning subgraphs be $T_1$ and $T_2$. Can there be another pair $T_3$ and $T_4$ of edge disjoint $2$-regular spanning subgraphs for the same graph? I mean that can we regard the existance of two edge disjoint $2$-regular spanning subgraphs as a unique existance?







      graph-theory finite-groups






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      edited Dec 3 '18 at 9:22









      Tianlalu

      3,08621038




      3,08621038










      asked Dec 3 '18 at 5:39









      Buddhini AngelikaBuddhini Angelika

      15710




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          Take $K_5$, the complete graph on $5$ vertices. Any cycle containing every vertex (Hamiltonian cycle if you are familiar with the terminology) and its complement exactly act as you describe. This graph contains more than $2$ Hamiltonian cycles, so this decomposition is not unique. Explicitly, if we take the vertices to be ${a,b,c,d,e}$, the decomposition into cycles $a-b-c-d-e-a$ and $a-c-e-b-d-a$ is distinct from the decomposition into $a-b-d-e-c-a$ and $a-d-c-b-e-a$.






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          • $begingroup$
            Thanks a lot @platty
            $endgroup$
            – Buddhini Angelika
            Dec 3 '18 at 8:24











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          $begingroup$

          Take $K_5$, the complete graph on $5$ vertices. Any cycle containing every vertex (Hamiltonian cycle if you are familiar with the terminology) and its complement exactly act as you describe. This graph contains more than $2$ Hamiltonian cycles, so this decomposition is not unique. Explicitly, if we take the vertices to be ${a,b,c,d,e}$, the decomposition into cycles $a-b-c-d-e-a$ and $a-c-e-b-d-a$ is distinct from the decomposition into $a-b-d-e-c-a$ and $a-d-c-b-e-a$.






          share|cite|improve this answer









          $endgroup$













          • $begingroup$
            Thanks a lot @platty
            $endgroup$
            – Buddhini Angelika
            Dec 3 '18 at 8:24
















          1












          $begingroup$

          Take $K_5$, the complete graph on $5$ vertices. Any cycle containing every vertex (Hamiltonian cycle if you are familiar with the terminology) and its complement exactly act as you describe. This graph contains more than $2$ Hamiltonian cycles, so this decomposition is not unique. Explicitly, if we take the vertices to be ${a,b,c,d,e}$, the decomposition into cycles $a-b-c-d-e-a$ and $a-c-e-b-d-a$ is distinct from the decomposition into $a-b-d-e-c-a$ and $a-d-c-b-e-a$.






          share|cite|improve this answer









          $endgroup$













          • $begingroup$
            Thanks a lot @platty
            $endgroup$
            – Buddhini Angelika
            Dec 3 '18 at 8:24














          1












          1








          1





          $begingroup$

          Take $K_5$, the complete graph on $5$ vertices. Any cycle containing every vertex (Hamiltonian cycle if you are familiar with the terminology) and its complement exactly act as you describe. This graph contains more than $2$ Hamiltonian cycles, so this decomposition is not unique. Explicitly, if we take the vertices to be ${a,b,c,d,e}$, the decomposition into cycles $a-b-c-d-e-a$ and $a-c-e-b-d-a$ is distinct from the decomposition into $a-b-d-e-c-a$ and $a-d-c-b-e-a$.






          share|cite|improve this answer









          $endgroup$



          Take $K_5$, the complete graph on $5$ vertices. Any cycle containing every vertex (Hamiltonian cycle if you are familiar with the terminology) and its complement exactly act as you describe. This graph contains more than $2$ Hamiltonian cycles, so this decomposition is not unique. Explicitly, if we take the vertices to be ${a,b,c,d,e}$, the decomposition into cycles $a-b-c-d-e-a$ and $a-c-e-b-d-a$ is distinct from the decomposition into $a-b-d-e-c-a$ and $a-d-c-b-e-a$.







          share|cite|improve this answer












          share|cite|improve this answer



          share|cite|improve this answer










          answered Dec 3 '18 at 5:53









          plattyplatty

          3,370320




          3,370320












          • $begingroup$
            Thanks a lot @platty
            $endgroup$
            – Buddhini Angelika
            Dec 3 '18 at 8:24


















          • $begingroup$
            Thanks a lot @platty
            $endgroup$
            – Buddhini Angelika
            Dec 3 '18 at 8:24
















          $begingroup$
          Thanks a lot @platty
          $endgroup$
          – Buddhini Angelika
          Dec 3 '18 at 8:24




          $begingroup$
          Thanks a lot @platty
          $endgroup$
          – Buddhini Angelika
          Dec 3 '18 at 8:24


















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