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Apr 27, 2023 at 14:00 comment added Derek Holt @DavidA.Craven Computing normal closure is polynomial time and fast in Magma. For general $O^\pi(G)$ that looks to be a good way to do it. For normal $p$-complements there is not much difference in performance between doing that and computing the lower central series, particularly when combined with Geoff's quick method for getting a negative answer.
Apr 26, 2023 at 11:57 comment added David A. Craven For constructing the $O^\pi(G)$, does the algorithm that sets $H=1$, choose a $\pi'$-elements at random, add to $H$, then take normal closure until $|G:H|$ is a $\pi$-number, work fast? Not sure how fast the normal closure algorithm is. $O^\pi(G)$ and $O_\pi(G)$ should be native commands in Magma, definitely.
Apr 24, 2023 at 18:15 vote accept Mare
Apr 24, 2023 at 18:15 comment added Mare Thanks. Magma is much faster than expected, even for such large groups.
Apr 23, 2023 at 16:18 history edited Derek Holt CC BY-SA 4.0
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Apr 22, 2023 at 19:02 comment added Carl-Fredrik Nyberg Brodda Oh, of course, I was in the GAP mindset. (Which, I suppose, works as a second answer)
Apr 22, 2023 at 13:25 history edited Derek Holt CC BY-SA 4.0
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Apr 22, 2023 at 13:24 comment added Derek Holt @Carl-FredrikNybergBrodda In fact $\mathtt{Sylow}$ exists as an abbreviation for $\mathtt{SylowSubgroup}$ in Magma, but I will edit it anyway to make it clearer.
Apr 22, 2023 at 12:36 comment added Carl-Fredrik Nyberg Brodda Should the second part not be $\texttt{IsNormal(G, SylowSubgroup(G,3))}$? Or perhaps you are using a package with a $\texttt{Sylow}$-function?
Apr 22, 2023 at 11:42 history answered Derek Holt CC BY-SA 4.0