Back last November, Dave Eaton <devo@vnet.ibm.com> wrote

Is there a program that allows you to type in Singmaster-style moves
and then prints out the resultant state, something like this (not
actual results):

INPUT:   (R U2 R3 U2)2
OUTPUT:  (fur,drb,rdf) (fr,dr)

I can't recall whether anyone offered such a thing or not. I think
there were some related programs, but nothing quite like this.

Anyway, there is now. :-)

Sample run:

% twist
> .set SLICER CUBER R' L
`SLICER' defined
> (SLICER U)4
Cube:
              u b u
              l u u
              u u u
        l u l f f f r r r b u b
        l l l f f f r r r b b b
        l l l f d f r r r b d b
              d f d
              d d d
              d b d
Cycles: (ub)+ (ul)+ (fd)+ (bd)+
Already centered
> .set WRENCH LAST
`WRENCH' defined
> WRENCH U WRENCH U'
Cube:
              u b u
              u u u
              u f u
        l l l f u f r r r b u b
        l l l f f f r r r b b b
        l l l f f f r r r b b b
              d d d
              d d d
              d d d
Cycles: (ub)+ (uf)+
Already centered
> (R U2 R3 U2)2
Cube:
              b u d
              f u u
              f u u
        r r r u f b l l r f b u
        l l l f f u r r r b b b
        l l l f f f l r r b b b
              d d u
              d d d
              d d d
Cycles: (ul,ur,fr) (ulb,urf,flu,frd,bru)
Already centered
> SLICER U
Cube:
              u u u
              f f f
              u u u
        f d f r r r b u b l l l
        l l l f d f r r r b u b
        l l l f d f r r r b u b
              d b d
              d b d
              d b d
Cycles: (u,b,d,f) (ub,bd,df,lu)+ (ur,uf)+ (ulb,ubr,urf,ufl)
Centred: (ul,fu,fr,dr,br,ur,fd,fl,dl,bl) (ulb,fur,lfd,ldb)+ (ubr,frd,drb)+ (ufl)+
> WRENCH CUBEU2 CUBEL WRENCH' (CUBEU2 CUBEL)'
Cube:
              u u u
              l u u
              u u u
        l u l f f f r r r b b b
        l l l f f r f r r b b b
        l l l f f f r r r b b b
              d d d
              d d d
              d d d
Cycles: (ul)+ (fr)+
Already centered
> 

The program is up for anonymous ftp from collatz.mcrcim.mcgill.edu in
/games/cube/twist.c. You have not a prayer of compiling it under
anything but gcc as it stands, though I think it would be relatively
easy (but perhaps rather ugly) to turn it into vanilla C. But with gcc
2.6.3, it builds fine for me on a Sun under SunOS 4.1.3 and a NeXT
under NeXT release 2.1, and probably most other machines too.

Read the comment header for a fuller description of its capabilities.

der Mouse

mouse@collatz.mcrcim.mcgill.edu