I have just realized that CubeGroup().faces("U") also goes counterclockwise
! what a mess !
On Thursday, March 19, 2015 at 1:07:12 PM UTC+1, Pierre wrote:
>
> Hi,
>
> I have just realized this, and thought it would be helpful to know for
> anyone playing with Sage's Rubik's cube abilitites. Here it is:
>
> While the following 3 commands:
>
> sage: CubeGroup().move("U")
>
> and
>
> sage: CubeGroup().plot3d_cube("U")
>
> and
>
> sage: RubiksCube().move("U").show3d()
>
> all take the convention that U means "move the face U clockwise",
> unfortunately the command
>
> sage: RubiksCube().move("U")
>
> assumes that U means "move the face U counter-clockwise".
>
> So yes, doing foo= RubiksCube().move("U") and printing foo displays
> something that is not consistent with what you get when calling
> foo.show3d().
>
> I thought it was something to do with 3d plotting being left-handed in
> Sage or whatever, but no, foo.show() also gives the "right" answer. And the
> convention for what the permutation U is, taken by CubeGroup and given in
> Joyner's book, is just not the one appearing when you print foo.
>
> It seems that inverses are taken, since RubiksCube().move("R*U") displays
> something that corresponds to U^-1 * R^-1 (by which I mean U^-1 first, then
> R^-1).
>
> In a nutshell: the __str__ method in RubiksCube seems to be broken,
> somehow.
>
> This is all quite confusing !
>
> best
> Pierre
>
>
>
>
>
>
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