[next] [prev] [up] Date: Thu, 11 Jun 81 03:23:00 -0400 (EDT)
[next] [prev] [up] From: Dan Hoey <Hoey@CMU-10A >
[next] ~~~ [up] Subject: Re: edge "flip" anyone...

Does anyone know of a way to flip two edges without changing
anything else, ie interchange the FR and FB edges, keeping their
same orientation.

The term "flip" generally means "change orientation" (of an
edge). I take it you mean "exchange" (or, acceptably,
"interchange"). This is provably not possible, because an exchange
is an odd permutation. I will send you the two messages which deal
with what can be done with a cube. (Anyone else who wants a copy,
request of Hoey@CMU-10A rather than the list.)

If you don't know what an even (or odd) permutation is, or
how it acts, any elementary algebra text should help. If you try
and fail, drop me a line and I'll try to help.

If not, how about one that will interchange FR and FB edges
without disturbing the top layer, but can mess up the bottom??

There is no FB edge. I'd guess you mean UR and UB, for
which RU'R' UUFFBB DDFFBB RUR' suffices.

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