added unfinished example 5.3_15

5.3_15.pl

+% nacteni:
+/* ['5.3_15.pl']. */
+
+?- op(600, xfx, --->).
+?- op(500, xfx, :).
+
+andor(Node,SolutionTree) :- biggest(Bound),expand(leaf(Node,0,0),Bound,SolutionTree,yes).
+
+% Case 1: bound exceeded, in all remaining cases F =< Bound
+expand(Tree,Bound,Tree,no) :- f(Tree,F),F>Bound,!.
+% Case 2: goal encountered
+expand(leaf(Node,F,_C),_,solvedleaf(Node,F),yes) :- goal(Node),!.
+% Case 3: expanding a leaf
+expand(leaf(Node,_F,C),Bound,NewTree,Solved) :- expandnode(Node,C,Tree1),!,
+    (expand(Tree1,Bound,NewTree,Solved);Solved=never,!).
+% Case 4: expanding a tree
+expand(tree(Node,_F,C,SubTrees),Bound,NewTree,Solved) :- Bound1 is Bound-C,
+    expandlist(SubTrees,Bound1,NewSubs,Solved1),
+    continue(Solved1,Node,C,NewSubs,Bound,NewTree,Solved).
+
+expandlist(Trees,Bound,NewTrees,Solved) :-
+    selecttree(Trees,Tree,OtherTrees,Bound,Bound1),
+    expand(Tree,Bound1,NewTree,Solved1),
+    combine(OtherTrees,NewTree,Solved1,NewTrees,Solved).
+
+continue(yes,Node,C,SubTrees,_,solvedtree(Node,F,SubTrees),yes) :-
+    bestf(SubTrees,H), F is C+H,!.
+continue(never,_,_,_,_,_,never) :- ! .
+continue(no,Node,C,SubTrees,Bound,NewTree,Solved) :- bestf(SubTrees,H),
+    F is C+H,!,expand(tree(Node,F,C,SubTrees),Bound,NewTree,Solved).
+    
+% slide 16
+
+combine(or:_,Tree,yes,Tree,yes) :- !.
+combine(or:Trees,Tree,no,or:NewTrees,no) :- insert(Tree,Trees,NewTrees),!.
+combine(or:[],_,never,_,never) :- ! .
+combine(or:Trees,_,never,or:Trees,no) :- !.
+combine(and:Trees,Tree,yes,and:[Tree|Trees],yes) :- allsolved(Trees),!.
+combine(and:_,_,never,_,never) :- ! .
+combine(and:Trees,Tree,_YesNo,and:NewTrees,no) :- insert(Tree,Trees,NewTrees),!.
+
+expandnode(Node,C,tree(Node,F,C,Op:SubTrees)) :- Node ---> Op:Successors,
+    evaluate(Successors,SubTrees),bestf(Op:SubTrees,H),F is C+H.
+    
+evaluate([],[]).
+evaluate([Node/C|NodesCosts],Trees) :- h(Node,H),F is C+H,evaluate(NodesCosts,Trees1),
+    insert( leaf(Node,F,C),Trees1,Trees).
+    
+allsolved([]).
+allsolved([Tree|Trees]) :- solved(Tree),allsolved(Trees).
+
+solved(solvedtree(_,_,_)).
+solved(solvedleaf(_,_)).
+
+% slide 17
+
+f(Tree,F) :- arg(2,Tree,F),! .
+
+insert(T ,[],[ T]) :- ! .
+insert(T,[T1|Ts],[T,T1|Ts]) :- solved(T1),!.
+insert(T,[T1|Ts],[T1|Ts1])  :- solved(T), insert(T,Ts,Ts1),! .
+insert(T,[T1|Ts],[T,T1|Ts]) :- f(T,F), f(T1,F1),F=<F1,!.
+insert(T,[T1|Ts],[T1|Ts1])  :- insert(T,Ts,Ts1).
+
+% First tree in OR-list is best
+bestf(or:[Tree|_], F) :- f(Tree,F), !.
+bestf(and:[],0) :- ! .
+bestf(and:[Tree1|Trees],F) :- f(Tree1,F1),bestf(and:Trees,F2),F is F1+F2,!.
+bestf(Tree,F) :- f(Tree,F).
+
+selecttree(Op:[Tree],Tree,Op:[],Bound,Bound) :- !. % The only candidate
+selecttree(Op:[Tree|Trees],Tree,Op:Trees,Bound,Bound1) :- bestf(Op:Trees,F),
+(Op=or,!,min(Bound,F,Bound1);Op=and,Bound1 is Bound-F).
+min(A,B,A) :- A<B,!.
+min(_A,B,B).
+

5.3_15.py

+#!/usr/bin/env python
+# encoding=utf-8 (pep 0263)
+
+# horni zavora pro cenu nejlepsi cesty
+biggest = 9999
+
+def andor(node):
+    sol, solved = expand(("leaf", node, 0, 0), biggest):
+    if solved == "yes":
+        return sol
+    else
+        raise ValueError("Reseni neexistuje.")
+
+def expand(tree, bound):
+    if f(tree) > bound:
+        return (tree, "no")
+    if tree[0] == "leaf":
+        _, node, f, c = tree
+        if f(tree) <= bound:
+            if is_goal(node):
+                return (("solvedleaf", node, f), "yes")
+            # ...
+
+def is_goal(x):
+    # zavisi na resenem problemu
+    return False