Definition:Rubik's Cube/Edge Facet

Definition

 * RubiksCubeFacets.png

Of each of the $9$ facets of each face of Rubik's cube, the $4$ on the edges of the face are called the edge facets.

The set of edge facets can be denoted $S_E$.

For example:
 * $fu$, $fr$, $fd$, $fl$ are the edge facets of the front face
 * $ul$, $ub$, $ur$, $uf$ are the edge facets of the up face

and so on.