# Fraction values around the vertices of a Loop's subdivision

In Loop's subdivision scheme, what do the variables $\alpha$ and $n$ refer to? Knowing what the variables refer to will help to derive the fractions around the vertices.

But, what do these fractions around the vertices, such as the one above, meant for?

The first image (above) should be this:

and shows the extraordinary case where the vertex point has valence $n$ ($n \neq 6$), i.e. there are $n$ points sharing an edge with it.

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