dijkstra-euclid.dyna

% Dijkstra's algorithm for single-source shortest path
path(start) min= 0.0.
path(B) min= path(A) + edge(A,B).
goal min= path(end).

% Euclidean distance on reachable pairs.
edge(A,B) := ((AX-BX)**(2.0) + (AY-BY)**(2.0))**(0.5)
             for pair(AX,AY) is pos(A),
                 pair(BX,BY) is pos(B),
                 reachable(A,B).

% Assert the position of some places on the map
pos("origin") := pair(0.0,0.0).
pos("t1"    ) := pair(1.0,2.0).
pos("PyTrip") := pair(3.0,4.0).
pos("t2"    ) := pair(2.0,3.5).

% separately, assert the adjacency graph
reachable("origin","t1").
reachable("origin","PyTrip").
reachable("t1"    ,"PyTrip").
reachable("PyTrip","t2").
reachable("t1"    ,"t2").

start := "origin".
end   := "t2".

% This file is mentioned in the tutorial!
% XREF:docs/sphinx/tutorial/dijkstra.rst