If $H$ is a subgroup with prime index $p$ of a finite simple group $G$, then $p$ is the maximal prime $p$...











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Let $G$ be a finite simple group. Let $H$ be a subgroup of $G$ whose index is a prime $p$. Prove that $p$ is the maximal prime dividing the order of $G$ and that $p^2 nmid |G|$.










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closed as off-topic by Derek Holt, amWhy, Rebellos, jgon, user10354138 Nov 20 at 1:04


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    Let $G$ be a finite simple group. Let $H$ be a subgroup of $G$ whose index is a prime $p$. Prove that $p$ is the maximal prime dividing the order of $G$ and that $p^2 nmid |G|$.










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    closed as off-topic by Derek Holt, amWhy, Rebellos, jgon, user10354138 Nov 20 at 1:04


    This question appears to be off-topic. The users who voted to close gave this specific reason:


    • "This question is missing context or other details: Please improve the question by providing additional context, which ideally includes your thoughts on the problem and any attempts you have made to solve it. This information helps others identify where you have difficulties and helps them write answers appropriate to your experience level." – Derek Holt, amWhy, Rebellos, jgon, user10354138

    If this question can be reworded to fit the rules in the help center, please edit the question.















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      Let $G$ be a finite simple group. Let $H$ be a subgroup of $G$ whose index is a prime $p$. Prove that $p$ is the maximal prime dividing the order of $G$ and that $p^2 nmid |G|$.










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      Let $G$ be a finite simple group. Let $H$ be a subgroup of $G$ whose index is a prime $p$. Prove that $p$ is the maximal prime dividing the order of $G$ and that $p^2 nmid |G|$.







      group-theory






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      edited Nov 19 at 15:52









      Tianlalu

      2,9361935




      2,9361935










      asked Nov 19 at 15:50









      mathnoob

      1,352116




      1,352116




      closed as off-topic by Derek Holt, amWhy, Rebellos, jgon, user10354138 Nov 20 at 1:04


      This question appears to be off-topic. The users who voted to close gave this specific reason:


      • "This question is missing context or other details: Please improve the question by providing additional context, which ideally includes your thoughts on the problem and any attempts you have made to solve it. This information helps others identify where you have difficulties and helps them write answers appropriate to your experience level." – Derek Holt, amWhy, Rebellos, jgon, user10354138

      If this question can be reworded to fit the rules in the help center, please edit the question.




      closed as off-topic by Derek Holt, amWhy, Rebellos, jgon, user10354138 Nov 20 at 1:04


      This question appears to be off-topic. The users who voted to close gave this specific reason:


      • "This question is missing context or other details: Please improve the question by providing additional context, which ideally includes your thoughts on the problem and any attempts you have made to solve it. This information helps others identify where you have difficulties and helps them write answers appropriate to your experience level." – Derek Holt, amWhy, Rebellos, jgon, user10354138

      If this question can be reworded to fit the rules in the help center, please edit the question.






















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          Solution: Consider the transitive action of $G$ on the left cosets of $H$. This induces a homomorphism $f: G rightarrow S_{p}$. But $G$ is simple, so $ker(f)$ is trivial or all of $G$. Since $f$ is not the zero map $G$ injects into $S_p$, so $|G|| p!$. That says that any prime decomposition of $|G|$ is less than or equals to $p$. Also $p^2 nmid p!$ so $p^2 nmid $|G|$.






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            1 Answer
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            active

            oldest

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            1 Answer
            1






            active

            oldest

            votes









            active

            oldest

            votes






            active

            oldest

            votes








            up vote
            3
            down vote













            Solution: Consider the transitive action of $G$ on the left cosets of $H$. This induces a homomorphism $f: G rightarrow S_{p}$. But $G$ is simple, so $ker(f)$ is trivial or all of $G$. Since $f$ is not the zero map $G$ injects into $S_p$, so $|G|| p!$. That says that any prime decomposition of $|G|$ is less than or equals to $p$. Also $p^2 nmid p!$ so $p^2 nmid $|G|$.






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              up vote
              3
              down vote













              Solution: Consider the transitive action of $G$ on the left cosets of $H$. This induces a homomorphism $f: G rightarrow S_{p}$. But $G$ is simple, so $ker(f)$ is trivial or all of $G$. Since $f$ is not the zero map $G$ injects into $S_p$, so $|G|| p!$. That says that any prime decomposition of $|G|$ is less than or equals to $p$. Also $p^2 nmid p!$ so $p^2 nmid $|G|$.






              share|cite|improve this answer

























                up vote
                3
                down vote










                up vote
                3
                down vote









                Solution: Consider the transitive action of $G$ on the left cosets of $H$. This induces a homomorphism $f: G rightarrow S_{p}$. But $G$ is simple, so $ker(f)$ is trivial or all of $G$. Since $f$ is not the zero map $G$ injects into $S_p$, so $|G|| p!$. That says that any prime decomposition of $|G|$ is less than or equals to $p$. Also $p^2 nmid p!$ so $p^2 nmid $|G|$.






                share|cite|improve this answer














                Solution: Consider the transitive action of $G$ on the left cosets of $H$. This induces a homomorphism $f: G rightarrow S_{p}$. But $G$ is simple, so $ker(f)$ is trivial or all of $G$. Since $f$ is not the zero map $G$ injects into $S_p$, so $|G|| p!$. That says that any prime decomposition of $|G|$ is less than or equals to $p$. Also $p^2 nmid p!$ so $p^2 nmid $|G|$.







                share|cite|improve this answer














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                share|cite|improve this answer








                edited Nov 22 at 20:37









                amWhy

                191k27223439




                191k27223439










                answered Nov 19 at 15:50









                mathnoob

                1,352116




                1,352116















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