A Lie algebra with trivial center and commutative radical

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Let $mathfrak g$ be a complex linear Lie algebra. Assume that the center $mathfrak z$ of $mathfrak g$ is trivial



Let $mathfrak r$ be the radical of $mathfrak g$. If $mathfrak r$ is abelian, then $mathfrak g$ is semisimple?



What if $mathfrak g$ is the Lie algebra of an algebraic complex linear group?










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    up vote
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    Let $mathfrak g$ be a complex linear Lie algebra. Assume that the center $mathfrak z$ of $mathfrak g$ is trivial



    Let $mathfrak r$ be the radical of $mathfrak g$. If $mathfrak r$ is abelian, then $mathfrak g$ is semisimple?



    What if $mathfrak g$ is the Lie algebra of an algebraic complex linear group?










    share|cite|improve this question

























      up vote
      3
      down vote

      favorite









      up vote
      3
      down vote

      favorite











      Let $mathfrak g$ be a complex linear Lie algebra. Assume that the center $mathfrak z$ of $mathfrak g$ is trivial



      Let $mathfrak r$ be the radical of $mathfrak g$. If $mathfrak r$ is abelian, then $mathfrak g$ is semisimple?



      What if $mathfrak g$ is the Lie algebra of an algebraic complex linear group?










      share|cite|improve this question















      Let $mathfrak g$ be a complex linear Lie algebra. Assume that the center $mathfrak z$ of $mathfrak g$ is trivial



      Let $mathfrak r$ be the radical of $mathfrak g$. If $mathfrak r$ is abelian, then $mathfrak g$ is semisimple?



      What if $mathfrak g$ is the Lie algebra of an algebraic complex linear group?







      lie-groups lie-algebras algebraic-groups






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      edited Sep 1 at 2:06

























      asked Sep 1 at 0:04









      Amrat A

      1135




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          Your question whether $mathfrakg$ is semisimple is equivalent to whether necessarily $mathfrakr = 0$. The answer is no. A counterexample is given by



          $$mathfrakg = lbrace pmatrixa & b & d\
          c& -a& e\
          0&0&0 : a,b,c,d,e in Bbb Crbrace$$



          where the radical
          $$mathfrakr = lbrace pmatrix0 & 0 & d\
          0& 0& e\
          0&0&0 : d,e in Bbb Crbrace$$
          is two-dimensional.






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            1 Answer
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            active

            oldest

            votes








            1 Answer
            1






            active

            oldest

            votes









            active

            oldest

            votes






            active

            oldest

            votes








            up vote
            1
            down vote



            accepted










            Your question whether $mathfrakg$ is semisimple is equivalent to whether necessarily $mathfrakr = 0$. The answer is no. A counterexample is given by



            $$mathfrakg = lbrace pmatrixa & b & d\
            c& -a& e\
            0&0&0 : a,b,c,d,e in Bbb Crbrace$$



            where the radical
            $$mathfrakr = lbrace pmatrix0 & 0 & d\
            0& 0& e\
            0&0&0 : d,e in Bbb Crbrace$$
            is two-dimensional.






            share|cite|improve this answer
























              up vote
              1
              down vote



              accepted










              Your question whether $mathfrakg$ is semisimple is equivalent to whether necessarily $mathfrakr = 0$. The answer is no. A counterexample is given by



              $$mathfrakg = lbrace pmatrixa & b & d\
              c& -a& e\
              0&0&0 : a,b,c,d,e in Bbb Crbrace$$



              where the radical
              $$mathfrakr = lbrace pmatrix0 & 0 & d\
              0& 0& e\
              0&0&0 : d,e in Bbb Crbrace$$
              is two-dimensional.






              share|cite|improve this answer






















                up vote
                1
                down vote



                accepted







                up vote
                1
                down vote



                accepted






                Your question whether $mathfrakg$ is semisimple is equivalent to whether necessarily $mathfrakr = 0$. The answer is no. A counterexample is given by



                $$mathfrakg = lbrace pmatrixa & b & d\
                c& -a& e\
                0&0&0 : a,b,c,d,e in Bbb Crbrace$$



                where the radical
                $$mathfrakr = lbrace pmatrix0 & 0 & d\
                0& 0& e\
                0&0&0 : d,e in Bbb Crbrace$$
                is two-dimensional.






                share|cite|improve this answer












                Your question whether $mathfrakg$ is semisimple is equivalent to whether necessarily $mathfrakr = 0$. The answer is no. A counterexample is given by



                $$mathfrakg = lbrace pmatrixa & b & d\
                c& -a& e\
                0&0&0 : a,b,c,d,e in Bbb Crbrace$$



                where the radical
                $$mathfrakr = lbrace pmatrix0 & 0 & d\
                0& 0& e\
                0&0&0 : d,e in Bbb Crbrace$$
                is two-dimensional.







                share|cite|improve this answer












                share|cite|improve this answer



                share|cite|improve this answer










                answered Sep 1 at 10:14









                Torsten Schoeneberg

                2,7551732




                2,7551732



























                     

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