When , namely in the maximal degeneration case, for simplicity we consider an -dimensional face of , such that there are only two -dimensional faces of containing , and they both lie on . Then the degree condition imposes a matching condition on the gradient of across the -dim face.
We consider a very concrete local example where ,
|
|
|
and the two divisors intersect transversely at , giving rise to the two -dimensional faces. All divisors are reduced. The complex geometric local model for comprises of two charts and . On the first chart for , and is the affine coordinate on . On the second chart for , , and is the affine coordinate on . The transition on the overlap is
|
|
|
The holomorphic volume form , and the coordinate . Locally on
|
|
|
On the two -dimensional faces the coordinates are and respectively, satisfying the linear constraints and , so we can eliminate . By adjusting we can make it zero in the local model. The potential satisfies the real MA equation on the two -dimensional faces:
|
|
|
and the problem is to match them on . The complex geometry suggests that the domain of the coordinates can be extended outside the original -simplices, by the identificaton
|
|
|
and the real MA equation is satisfied also on . In terms of gradients at ,
|
|
|
The first conditions merely mean the tangent derivatives along agree. The normal derivative matching condition precisely says
|
|
|
From a different perspective, the zero degree condition explains why can be invisible to the metric, so is allowed to remain smooth across .