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I am trying to prove the following result:

Let $G$ be a primitive permutation group on $\Omega$ of degree $n$ that contains a cycle $g$ fixing $k \geq 3$ points. Then, $A_n \leq G$ where $A_n$ is the alternating subgroup of degree $n$.

This is a generalisation of Jordan's theorem in which the cycle is of prime length. The generalisation has been achieved in a paper by Gareth Jones (2013) in a more general theorem that also deals with the cases of $k \in \{0,1,2 \}$. The proof, however relies on the classification of finite simple groups, which I would like to avoid using if possible. I have managed to show that the theorem is implied by induction if I can prove the base case of $k = 3$, and also that this base case is true if such a group must contain any element of degree strictly less than 5 (where the degree of a group element is the number of points moved by the element). This is where I am stuck. Of course, since this theorem is true, clearly such an element must exist but I am not sure how to show this. I might be hitting a dead end here if the classification of finite simple groups is an essential tool in proving even this simplified version, but I still want to give it a shot.

Any suggestions or insight will help. Also, if anybody has a good reason why this would be a dead end without application of the classification of finite simple groups, this would also be good to know! Specifically I am trying to show that either the case $k=3$ is true or that if $k = 3$, then $G$ contains an element that moves at most four points. I know that such a group is 4-fold transitive and I also know how to show that it is true when the length of the cycle $g$ is less than 5. I have tried a lot of the methods used in the proofs of theorems in Wielandt's book Finite Permutation Groups, specifically those in chapter 13, but nothing seems to work.

TissuePaper
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  • Also, finding an element that contains a four-cycle, two transpositions or a single transposition in its cycle decomposition in which every other cycle in the decomposition is odd length implies that an element moving just four points or two points exists. Similarly, any element containing a three-cycle in the decomposition where all other cycles in the decomposition are not divisible by three implies a three cycle exists. I am thinking that using an element of degree $n$ implied by another of Jordan's theorems along with $g$ and 4-fold transitivity might work. – TissuePaper Nov 21 '21 at 09:50

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