SWI Prolog homework

I am a software engineer (Java) and a friend asked for my help with a SWI Prolog homework assignment dealing with path finding (astar). The algorithm is pretty simple, you just choose the next edge based on the next shortest path (factoring in a straight line distance heuristic to the edge where this function/rule is provided), but the recursive nature of prolog and creating rules makes it more of a challenge. There is psuedo code, notes, and a prolog graph configuration prolog file. There are also several stubs for the entry point, notes on the start state configuration structure and several slides. The assignment is just to implement the remaining rules commented by psuedo code which is estimated at 40 lines of code left per the instructions. I am thinking an experienced prolog programmer could knock this out in an hour or so. SOLUTION MUST BE IN SWI PROLOG AND FOLLOW THE TEMPLATED RULES PROVIDED. Sample program stub with psuedo code shown on this post and further documents will be provided upon hire.