Path query_infer(Graph G, Concept currentConcept, Concept finalConcept, Path path, bool isA)
{
    Concept[] adjTrue = currentConcept.get_adjTrue;
    Concept[] adjFalse = currentConcept.get_adjFalse;
    Concept[] adj = adjTrue ~ adjFalse;

    Concept closestConcept = finalConcept;

    if(currentConcept.compare_concept(finalConcept))
        return path;

    if(!isA)
        return path;

    if(adj.length > 0)
    {
        while(adj.length > 0)
        {
            int closestIndex = 0;

            foreach(index, c; adj)
            {
                closestConcept = closest(G, currentConcept, closestConcept, c);
                closestIndex = index;
            }

            if(adjFalse.contain_concept(closestConcept))
                isA = false;

            path.add(closestConcept);

            query_infer(G, closestConcept, finalConcept, path, isA);
            isA = true;

            if(!path.get_tail.get_concept.compare_concept(finalConcept))
            {
                path.pop;
                adj = adj[0..closestIndex] ~ adj[closestIndex+1..$];
            }
            else
                return path;
        }
    }
    return path;
}

Concept closest(Graph G, Concept currentConcept, Concept nextA, Concept nextB)
{
    Edge query = new Edge(currentConcept, nextA, true);

    if(currentConcept.get_adjFalse.contain_concept(nextB))
        return nextB;

    Path[] pathList = [];
    pathList = query_path(query, G, false);

    foreach(p; pathList)
        if(p.get_conceptList[0..$-1].contain_concept(nextB))
            return nextB;
    return nextA;
}