Information Technology Reference
In-Depth Information
(1) three actions: Load, Wait, and Shoot;
(2) two fluents: Alive and Loaded;
(3) two effect axioms: the Load action puts a bullet in the gun, and the victim
dies after a Shoot action so long as the gun is loaded at the time, I.e.:
Y 1 : Holds(Loaded, Result(Load,
s
))
(2.32)
Y 2 : ¬Holds(Alive, Result(Shoot,
s
)) â Holds( Loaded,
s
)
(2.33)
(4) two observation sentences about the initial situation S0: the victim is alive in
the initial situation, and the gun is unloaded, i.e.:
Y 3 : Hold(Alive, S 0 )
(2.34)
Y 4 : ¬Holds(Loaded, S 0 )
(2.35)
Finally, a predicate UNA is introduced to guarantee the nuiqueness of names
of actions and fluents. Formally, UNA(
f 1 , f 2 , …, f k ) is defined as:
f
i (
x
1 ,
x
2 , ..,
x
m ) ≠
f
j (
y
1 ,
y
2 , …,
y
n )
for all
i
<
j
<
k
, and
n )
for all i<k. With the predicate UNA, the following formulas are added for the
Yale shooting problem:
Y 5 : UNA(Load, Wait, Shoot) (2.36)
f
i (
x
1 ,
x
2 , ..,
x
n ) =
f
i (
y
1 ,
y
2 , …,
y
n ) ã (
x
1 =
y
1
x
2 =
y
2 ∧…∧
x
n =
y
Y 6 : UNA(Alive, Loaded) (2.37)
Y 7 : UNA(S 0 , Result) (2.38)
Now, consider the situation that obtains after the sequence of actions: Load,
Wait, Shoot, i.e., consider the situation Result(Shoot, Result(Wait, Result(Load,
S0))). What fluents hold in this situation if the circumscription polic is applied to
these formulas? Intuitively, the gun will be loaded after the Load action, it still to
be Loaded after the Wait action, and the victim will be die after the Shoot action,
Search WWH ::




Custom Search