## The Professor's Cube

### IV. Solve the Top Inner Edges

There are 4 inner-edges that have to be placed on the top layer, one at a time. If the edge is on the bottom layer, then rotate the bottom layer until that edge appears in the front, dircetly below its destination. An inner-edge can be flipped around two different ways, so there are two different moves used to climb it to the top.

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## B- N- B+ N+

An inner-edge can also appear at the "equator" of the puzzle. It can start from two different places, so once again there are two different moves to navigate it to the top. You may have to rotate the top layer to match the diagrams below.

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## N- B+ R- B-N+ B+ R+

Note: these moves are optional and are provided only as shortcuts. You can bypass this section by knocking an edge down from the equator (next section), and moving it up to the top layer (previous section) afterwards. On the plus-side, you have less moves to memorize. On the minus-side, you have to do twice as much work.

The inner-edge you want to move may not always on the bottom layer. Sometimes it can appear at the equator of the puzzle; other times it can already be on the top layer, but on the wrong side. Either way it must be knocked down, so you can climb it up to the correct spot later on.

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## N- B- R- B+N+ B- R+

And finally, you may need to invert an inner-edge that is already in place.

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## N- B2 N+ B-N- B+ N+

After arranging all the top inner-edges, the entire Top Side should be completed. Congratulations! Even just solving one side is enough to stun anyone in total awe.

If you want, you can scramble the cube and re-do the top side again, as practice makes perfect. By re-solving the top layer, you become more accustomed with the Professor's Cube and the moves that solve it. It also builds up an arsenal of ammunition that conquer the later steps.

Q: Why do I have to solve the top inner-edges last?

A: You don't. You can solve the inner-edges before doing the outer-edges or even the top corners. You can even alternate (edge, corner, edge, corner, etc.) the solution steps if you want. The moves for solving the top corners and top edges were carefully selected so that they do not interfere with each other; as some prefer to finish a row of cubelets for each side. However, you MUST finish the entire top side before solving the...
Middle Outer-Edges.