Group Isomorphism regarding Sylow Subgroups











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Suppose I have given two groups say, $G_1,G_2$ such that they have same order.I'm assuming they are non commutative.Then their Syllow subgroups has same order clearly.If I'm given that the number of Syllow subgroups of these are also same then "are $G_1,G_2$ isomorphic"? I have always find this statement as true considering lower order groups but can't proved it. Is it true or there are some counterexamples too! Thanks for reading.










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    Suppose I have given two groups say, $G_1,G_2$ such that they have same order.I'm assuming they are non commutative.Then their Syllow subgroups has same order clearly.If I'm given that the number of Syllow subgroups of these are also same then "are $G_1,G_2$ isomorphic"? I have always find this statement as true considering lower order groups but can't proved it. Is it true or there are some counterexamples too! Thanks for reading.










    share|cite|improve this question


























      up vote
      3
      down vote

      favorite









      up vote
      3
      down vote

      favorite











      Suppose I have given two groups say, $G_1,G_2$ such that they have same order.I'm assuming they are non commutative.Then their Syllow subgroups has same order clearly.If I'm given that the number of Syllow subgroups of these are also same then "are $G_1,G_2$ isomorphic"? I have always find this statement as true considering lower order groups but can't proved it. Is it true or there are some counterexamples too! Thanks for reading.










      share|cite|improve this question















      Suppose I have given two groups say, $G_1,G_2$ such that they have same order.I'm assuming they are non commutative.Then their Syllow subgroups has same order clearly.If I'm given that the number of Syllow subgroups of these are also same then "are $G_1,G_2$ isomorphic"? I have always find this statement as true considering lower order groups but can't proved it. Is it true or there are some counterexamples too! Thanks for reading.







      abstract-algebra group-isomorphism sylow-theory






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      edited Dec 5 at 19:17









      Ethan Bolker

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      40.7k546108










      asked Dec 5 at 19:06









      Subhajit Saha

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          This is easily seen to fail for abelian groups, since all abelian groups of a given order have the same number of Sylow subgroups. For a nonabelian example, consider two distinct nonabelian groups of order $p^n$ for some prime $p$ and integer $n$.






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          • Ok! But what about those cases if we have distinct syllow subgroups of different order
            – Subhajit Saha
            Dec 5 at 19:55










          • @Sub I don't have an example, but I'm $100%$ certain the numbers of Sylow subgroups doesn't classify the group, abelian or not. It would make the group isomorphism problem easy, which it isn't.
            – Matt Samuel
            Dec 5 at 20:14


















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          Groups with Identical Subgroup Lattices in All Powers shows there are many, many examples even when the Sylow subgroups are required to be cyclic.






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          • @MattSamuel D'oh. You are correct.
            – Eric Towers
            Dec 5 at 19:20










          • Sir,I said both of them as non Abelian , further you have done a mistake saying $S_3$ has unique $2-$ Syllow subgroups.
            – Subhajit Saha
            Dec 5 at 19:25










          • @SubhajitSaha : All Sylow subgroups cyclic implies metacyclic, which does not imply abelian.
            – Eric Towers
            Dec 5 at 21:43











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          2 Answers
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          2 Answers
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          up vote
          4
          down vote



          accepted










          This is easily seen to fail for abelian groups, since all abelian groups of a given order have the same number of Sylow subgroups. For a nonabelian example, consider two distinct nonabelian groups of order $p^n$ for some prime $p$ and integer $n$.






          share|cite|improve this answer





















          • Ok! But what about those cases if we have distinct syllow subgroups of different order
            – Subhajit Saha
            Dec 5 at 19:55










          • @Sub I don't have an example, but I'm $100%$ certain the numbers of Sylow subgroups doesn't classify the group, abelian or not. It would make the group isomorphism problem easy, which it isn't.
            – Matt Samuel
            Dec 5 at 20:14















          up vote
          4
          down vote



          accepted










          This is easily seen to fail for abelian groups, since all abelian groups of a given order have the same number of Sylow subgroups. For a nonabelian example, consider two distinct nonabelian groups of order $p^n$ for some prime $p$ and integer $n$.






          share|cite|improve this answer





















          • Ok! But what about those cases if we have distinct syllow subgroups of different order
            – Subhajit Saha
            Dec 5 at 19:55










          • @Sub I don't have an example, but I'm $100%$ certain the numbers of Sylow subgroups doesn't classify the group, abelian or not. It would make the group isomorphism problem easy, which it isn't.
            – Matt Samuel
            Dec 5 at 20:14













          up vote
          4
          down vote



          accepted







          up vote
          4
          down vote



          accepted






          This is easily seen to fail for abelian groups, since all abelian groups of a given order have the same number of Sylow subgroups. For a nonabelian example, consider two distinct nonabelian groups of order $p^n$ for some prime $p$ and integer $n$.






          share|cite|improve this answer












          This is easily seen to fail for abelian groups, since all abelian groups of a given order have the same number of Sylow subgroups. For a nonabelian example, consider two distinct nonabelian groups of order $p^n$ for some prime $p$ and integer $n$.







          share|cite|improve this answer












          share|cite|improve this answer



          share|cite|improve this answer










          answered Dec 5 at 19:18









          Matt Samuel

          36.6k63464




          36.6k63464












          • Ok! But what about those cases if we have distinct syllow subgroups of different order
            – Subhajit Saha
            Dec 5 at 19:55










          • @Sub I don't have an example, but I'm $100%$ certain the numbers of Sylow subgroups doesn't classify the group, abelian or not. It would make the group isomorphism problem easy, which it isn't.
            – Matt Samuel
            Dec 5 at 20:14


















          • Ok! But what about those cases if we have distinct syllow subgroups of different order
            – Subhajit Saha
            Dec 5 at 19:55










          • @Sub I don't have an example, but I'm $100%$ certain the numbers of Sylow subgroups doesn't classify the group, abelian or not. It would make the group isomorphism problem easy, which it isn't.
            – Matt Samuel
            Dec 5 at 20:14
















          Ok! But what about those cases if we have distinct syllow subgroups of different order
          – Subhajit Saha
          Dec 5 at 19:55




          Ok! But what about those cases if we have distinct syllow subgroups of different order
          – Subhajit Saha
          Dec 5 at 19:55












          @Sub I don't have an example, but I'm $100%$ certain the numbers of Sylow subgroups doesn't classify the group, abelian or not. It would make the group isomorphism problem easy, which it isn't.
          – Matt Samuel
          Dec 5 at 20:14




          @Sub I don't have an example, but I'm $100%$ certain the numbers of Sylow subgroups doesn't classify the group, abelian or not. It would make the group isomorphism problem easy, which it isn't.
          – Matt Samuel
          Dec 5 at 20:14










          up vote
          2
          down vote













          Groups with Identical Subgroup Lattices in All Powers shows there are many, many examples even when the Sylow subgroups are required to be cyclic.






          share|cite|improve this answer























          • @MattSamuel D'oh. You are correct.
            – Eric Towers
            Dec 5 at 19:20










          • Sir,I said both of them as non Abelian , further you have done a mistake saying $S_3$ has unique $2-$ Syllow subgroups.
            – Subhajit Saha
            Dec 5 at 19:25










          • @SubhajitSaha : All Sylow subgroups cyclic implies metacyclic, which does not imply abelian.
            – Eric Towers
            Dec 5 at 21:43















          up vote
          2
          down vote













          Groups with Identical Subgroup Lattices in All Powers shows there are many, many examples even when the Sylow subgroups are required to be cyclic.






          share|cite|improve this answer























          • @MattSamuel D'oh. You are correct.
            – Eric Towers
            Dec 5 at 19:20










          • Sir,I said both of them as non Abelian , further you have done a mistake saying $S_3$ has unique $2-$ Syllow subgroups.
            – Subhajit Saha
            Dec 5 at 19:25










          • @SubhajitSaha : All Sylow subgroups cyclic implies metacyclic, which does not imply abelian.
            – Eric Towers
            Dec 5 at 21:43













          up vote
          2
          down vote










          up vote
          2
          down vote









          Groups with Identical Subgroup Lattices in All Powers shows there are many, many examples even when the Sylow subgroups are required to be cyclic.






          share|cite|improve this answer














          Groups with Identical Subgroup Lattices in All Powers shows there are many, many examples even when the Sylow subgroups are required to be cyclic.







          share|cite|improve this answer














          share|cite|improve this answer



          share|cite|improve this answer








          edited Dec 5 at 19:20

























          answered Dec 5 at 19:16









          Eric Towers

          31.7k22265




          31.7k22265












          • @MattSamuel D'oh. You are correct.
            – Eric Towers
            Dec 5 at 19:20










          • Sir,I said both of them as non Abelian , further you have done a mistake saying $S_3$ has unique $2-$ Syllow subgroups.
            – Subhajit Saha
            Dec 5 at 19:25










          • @SubhajitSaha : All Sylow subgroups cyclic implies metacyclic, which does not imply abelian.
            – Eric Towers
            Dec 5 at 21:43


















          • @MattSamuel D'oh. You are correct.
            – Eric Towers
            Dec 5 at 19:20










          • Sir,I said both of them as non Abelian , further you have done a mistake saying $S_3$ has unique $2-$ Syllow subgroups.
            – Subhajit Saha
            Dec 5 at 19:25










          • @SubhajitSaha : All Sylow subgroups cyclic implies metacyclic, which does not imply abelian.
            – Eric Towers
            Dec 5 at 21:43
















          @MattSamuel D'oh. You are correct.
          – Eric Towers
          Dec 5 at 19:20




          @MattSamuel D'oh. You are correct.
          – Eric Towers
          Dec 5 at 19:20












          Sir,I said both of them as non Abelian , further you have done a mistake saying $S_3$ has unique $2-$ Syllow subgroups.
          – Subhajit Saha
          Dec 5 at 19:25




          Sir,I said both of them as non Abelian , further you have done a mistake saying $S_3$ has unique $2-$ Syllow subgroups.
          – Subhajit Saha
          Dec 5 at 19:25












          @SubhajitSaha : All Sylow subgroups cyclic implies metacyclic, which does not imply abelian.
          – Eric Towers
          Dec 5 at 21:43




          @SubhajitSaha : All Sylow subgroups cyclic implies metacyclic, which does not imply abelian.
          – Eric Towers
          Dec 5 at 21:43


















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