One issue is that f-id is not a ring homomorphism. So do I restrict to a range of degrees, convert to vector spaces, and compute the kernel? I'm not sure of the right approach.
On Thursday, August 25, 2022 at 3:11:12 AM UTC-7 pedrito...@gmail.com wrote: > Dear John, > Wouldn’t be of some help to consider the kernel of f-Id (with Id the > identity map)? > Best, > Pedro > > El El jue, 25 ago 2022 a las 8:22, Dima Pasechnik <dim...@gmail.com> > escribió: > >> >> >> On Thu, 25 Aug 2022, 00:38 John H Palmieri, <jhpalm...@gmail.com> wrote: >> >>> I have a polynomial ring R = k[x1, x2, ..., xn] and a ring homomorphism >>> f: R -> R. In case it matters, k=GF(2). I would like to find the subring of >>> elements x satisfying f(x) = x: that is, I want to find the equalizer of >>> the pair of maps (f, 1). Is there anything in Sage that will compute this? >>> The more polynomial generators this can handle, the better. >>> >> >> Is this subring finitely generated? Invariant theory in positive >> characteristic is full of surprises... >> >> >>> -- >>> John >>> >>> -- >>> 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 sage-support...@googlegroups.com. >>> To view this discussion on the web visit >>> https://groups.google.com/d/msgid/sage-support/6b028ddf-d0b7-4156-adad-7315cc6220a1n%40googlegroups.com >>> >>> <https://groups.google.com/d/msgid/sage-support/6b028ddf-d0b7-4156-adad-7315cc6220a1n%40googlegroups.com?utm_medium=email&utm_source=footer> >>> . >>> >> -- >> 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 sage-support...@googlegroups.com. >> > To view this discussion on the web visit >> https://groups.google.com/d/msgid/sage-support/CAAWYfq3d%3DLMGOoXUyPhqRgzWfcMvrc%3DWZrxOTN7rfBg71VL06Q%40mail.gmail.com >> >> <https://groups.google.com/d/msgid/sage-support/CAAWYfq3d%3DLMGOoXUyPhqRgzWfcMvrc%3DWZrxOTN7rfBg71VL06Q%40mail.gmail.com?utm_medium=email&utm_source=footer> >> . >> > -- 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 sage-support+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/sage-support/8def5bf5-9526-49ee-b280-3203e2dd4949n%40googlegroups.com.
