Changes

== PM2 Quadtree ==

== PM2 Quadtree ==

A PM2 Quadtree follows the following rules:

A PM2 Quadtree follows the following rules:

# At most, one vertex can lie in a region represented by a quadtree leaf node.

# At most, one vertex can lie in a region represented by a quadtree leaf node.

# If a quadtree leaf node's region contains no vertices, then it can contain only q-edges that meet at a common vertex exterior to the region.

# If a quadtree leaf node's region contains no vertices, then it can contain only q-edges that meet at a common vertex exterior to the region.

# Each region's quadtree leaf node is maximal.

# Each region's quadtree leaf node is maximal.

== PM3 Quadtree ==

== PM3 Quadtree ==