I think the author uses "present" to say "generate" Il giorno mercoledì 24 marzo 2021 alle 09:35:05 UTC+1 vdelecroix ha scritto:
> What does it mean "it presents Z5"? > > Le 24/03/2021 à 09:28, Mattia Villani a écrit : > > That matrix comes from the paper by J.Hempel: "Homology of covering" Pac. > > J. Math. vol 112 (1984) 83, example 5.2. > > The author says that it presents Z5 > > > > Il giorno mercoledì 24 marzo 2021 alle 08:50:18 UTC+1 vdelecroix ha > scritto: > > > >> Your matrix has determinant 4 - 9 = -5. Hence, the group it generates > >> in GL(2,QQ) is necessarily infinite. > >> > >> Le 24/03/2021 à 08:47, Mattia Villani a écrit : > >>> I do not have real code, only a matrix: > >>> > >>> matrix([[1,-3],[-3,4]]) > >>> > >>> which should be a representation of the group Z5: I want to verify it > >> with > >>> Sage > >>> > >>> Il giorno martedì 23 marzo 2021 alle 17:18:12 UTC+1 [email protected] > ha > >>> scritto: > >>> > >>>> On Tue, Mar 23, 2021 at 2:00 PM Mattia Villani <[email protected]> > >> wrote: > >>>>> > >>>>> Is is possible to find the group given the matrix presentation? > >>>> > >>>> Please be more specific. Post some Sage commands you're trying. > >>>> > >>>>> > >>>>> -- > >>>>> You received this message because you are subscribed to the Google > >>>> Groups "sage-support" group. > >>>>> To unsubscribe from this group and stop receiving emails from it, > send > >>>> an email to [email protected]. > >>>>> To view this discussion on the web visit > >>>> > >> > https://groups.google.com/d/msgid/sage-support/348e69d5-b3a5-45c4-a7ec-baed9213f6dcn%40googlegroups.com > >>>> . > >>>> > >>> > >> > > > -- You received this message because you are subscribed to the Google Groups "sage-support" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/sage-support/38ad34e7-d9bc-4541-8729-fd665a9ee0b4n%40googlegroups.com.
