basic network notations

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maximal planar network

with basic network notations

fact1
each link belongs to 2 regions(seperating), therefore define \(\text{region } f \in \text{ set of all regions } F\) \[ \sum_{f \in F}{size(f)} = 2 m \]
fact2
define all regions have at least \(g\) sides, then \[ g r \le \sum_{f \in F}{size(f)} = 2 m \]
fact3

the to subsitute \(r = 2 - n + m\), then \[ g(2-n+m) \le 2m \]

which rearranges to

\[ m \le \frac{g}{g-2}(n-2) \]

which defines the upper bound of the number of links in a planar network, equality holds when all regions are of the same size \(g\).

Author: Linfeng He

Created: 2024-04-03 Wed 23:16