Oracles can be used to guide the search for solutions of the XDK solver. They are stand-alone programs acting as a server to be asked by a client (= the XDK solver) to choose one among a number of possibilities for further search.
Oracles and the XDK solver communicate over a socket. The socket port to be used can be set upon start of the oracle, and must be the same as set for the XDK solver.
This is work in progress. At the moment, we have only one oracle viz. the manual oracle which allows the user to determine the path through the search tree.