To implement M_R in Sage would be non-trivial, since it is a pair of moves followed by a solid cube rotation. The rotation changes *all* the moves which follow it. So to implement X*M_R*Y (reading left-to-right) in Sage you'd have to change Y.
I've done it in a few cases to check moves but it is always a pain. Maybe someone could write a move converter? Glad you like the book! 50% of the royalties go directly to Sage and the remainder go to EII (earthisland.org). On Wed, Feb 25, 2009 at 4:37 AM, Pierre <pierre.guil...@gmail.com> wrote: > > hi there, > > sorry if this is not really sage-related (it is in a way). > > So David, i'm currently reading your book "adventures in group > theory", and i'm thoroughly enjoying it. I'm sure it will also be of > great help when i finally teach sage in my university (the switch from > maple is about to happen, maybe next year!) > > there is something puzzling me though, if i may say so... It's the > movement M_R. As you describe it, it moves the middle slice... > therefore moving the central facets, so strictly speaking it's > certainly not a move in the cube's group. I understand that you can > almost get the same effect by moving the left and right faces in the > opposite direction, so something like LR^-1 if i get the orientations > right. However, there is a difference, in that you need to look at the > cube from another angle if you want to get the feeling that it's the > middle slice that's just moved. In doing so, the next moves U, F ... > become ambiguous to me, as i don't know what the "front" is anymore. > > i've tried this with sage, following section 5.1.1, p287, trying to > "flip the top edges uf, ub": > > sage: rubik = CubeGroup() > sage: r= rubik.R() > sage: l= rubik.L() > sage: u= rubik.U() > sage: d= rubik.D() > sage: f= rubik.F() > sage: b= rubik.B() > sage: mr = r^(-1)*l > sage: flip= (mr*u)^3*u*(mr^(-1)*u)^3*u > sage: P= rubik.plot3d_cube(flip); show(P) > > the result is a bit of a mess. > > what am i getting wrong ? > > thanks ! > Pierre > > > --~--~---------~--~----~------------~-------~--~----~ To post to this group, send email to sage-support@googlegroups.com To unsubscribe from this group, send email to sage-support-unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/sage-support URLs: http://www.sagemath.org -~----------~----~----~----~------~----~------~--~---
