Certainly with a good cube you _could_ hold the outside and push to twist a center slice. From www.cube20.org -- "We consider any twist of any face to be one m

Certainly with a good cube you _could_ hold the outside and push to twist a center slice. From www.cube20.org -- "We consider any twist of any face to be one move (this is known as the half-turn metric.)" Also, "New results: God's Number is 26 in the quarter turn metric!"