- 最后登录
- 2010-8-10
- 在线时间
- 24 小时
- 阅读权限
- 10
- 注册时间
- 2009-4-27
- 积分
- 94
- 帖子
- 58
- 精华
- 0
- UID
- 89592
- 性别
- 保密
- 积分
- 94
- 帖子
- 58
- 精华
- 0
- UID
- 89592
- 性别
- 保密
|
33楼那个(R MD )4( U MF)4 (B MR')4不错啊，怎么这么简单
转动魔方 重复使用 同一个简单的公式
It can be proven by counting arguments that there exist positions needing at least 18 moves to solve. To show this, first count the number of cube positions that exist in total, then count the number of positions achievable using at most 17 moves. It turns out that the latter number is smaller.
This argument was not improved upon for many years. Also, it is not a constructive proof: it does not exhibit a concrete position that needs this many moves. It was conjectured that the so-called superflip would be a position that is very difficult. The superflip is a position on the cube where all the cubies are in their correct position, all the corners are correctly oriented but each edge is oriented the wrong way.
One indication that this might be the case is that it is the only element other than the identity that is in the center of the cube group.
In 1992 a solution for the superflip with 20 face turns was found by Dik T. Winter. In 1995, Michael Reid proved its minimality, thereby giving a new lower bound for the diameter of the cube group.
Also in 1995, a solution for superflip in 24 quarter turns was found by Michael Reid, its minimality was proven by Jerry Bryan. [1]
In 1998 Michael Reid found a new position requiring more than 24 quarter turns to solve. The position, named by him as 'superflip composed with four spot' needs 26 quarter turns. [2]
[ 本帖最后由 bardy 于 2009-5-13 20:42 编辑 ] |
|
IP卡
狗仔卡
发表于 2009-5-12 20:34:21
恢复卡
发表于 2009-5-12 23:03:52
发表于 2009-5-13 10:12:18
