Module reachability_solver::etch

Etching - A technique to iterate through a maze by removing nodes

Etching is a technique to iterate through a maze by removing either initial or terminal nodes.

The maze solution contains information about which nodes that are initial and terminal. This information can be used to change the original maze. Solving the new maze yields a different solution than the previous one.

The purpose of etching is to analyze a maze without looking at the original. Various techniques for etching puts restrictions to what kind of knowledge is obtained.

Functions

cardinality	Measures the cardinality of a maze by removing initial nodes repeatedly, until there are no edges left.
initial	Etches away initial nodes.
terminal	Etches away terminal nodes.