KogSys-IA-B: Intelligente Agenten
Schmid, Siebers
SS 14
6. Assignment
Hand in online in the vc-course before the practice on July 2, 2014.
1 The Rocket-Problem
The rocket-problem is a transportation problem. Initially there are two crates standing
on the earth. The goal is to bring those crates on the surface of the moon. Crates can
be loaded in and unloaded from a rocket. The rocket can fly to the moon.
The following is a (reduced) set-theoretic representation of this problem. The crates are
noted as c1 and c2, negation is denoted by a tilde (~):
Atoms:
c1_earth, c1_moon, c2_earth, c2_moon,
loaded_c1, loaded_c2,
rocket_earth, rocket_moon
Operators
load_c1
;; Loades crate 1 in the rocket
preconds: c1_earth, rocket_earth
effects: loaded_c1, ~c1_earth
load_c2
;; Loades crate 2 in the rocket
preconds: c2_earth, rocket_earth
effects: loaded_c2, ~c2_earth
fly
;; The rocket flies to the moon
preconds: rocket_earth
effects: rocket_moon, ~rocket_earth
1
unload_c1
;; Unloads crate 1
preconds: rocket_moon, loaded_c1
effects: ~loaded_c1, c1_moon
unload_c2
;; Unloads crate 2
preconds: rocket_moon, loaded_c2
effects: ~loaded_c2, c2_moon
Using this representation the goal is given by g = {c1 moon, c2 moon }. Planning starts
with the sate s0 = {c1 earth, c2 earth, rocket earth}.
2 Heuristics
During planning some planning algortihm expands the state s = {loaded c1, c2 earth,
rocket earth}. Possible successor states are
s1 = {c1 earth, c2 earth, rocket earth}
s2 = {loaded c1, loaded c2, rocket earth}
s3 = {loaded c1, c2 earth, rocket moon}
The state s1 is eliminated by loop detection.
2.1 Delta 0 (4 Points)
Which of the states s2 and s3 is better according to ∆0 ?
2.2 Delta 1 (4 Points)
Which of the states s2 and s3 is better according to ∆1 ?
3 Graphplan (8 Points)
Start building a Planning Graph with the starting state s0 = {loaded c1, c2 earth,
rocket earth}. Complete the graph until state-level 2. Include the mutex-links for statelevel 1 and the action-levels 1 and 2 in your graph. Use another color for the mutex links
(not red!).
2