Situational Calculus
Plans by Proof - due to John McCarthy, 1963
Σ= (S, A, O)
where S - set of
situations
,
A
- set of Actions,
O
- set of objects.
Preconditions of an action are written as
Poss(a(o), s) → F(o, s), s ∈ S, a ∈ A, o ∈ O
Example:
Poss(drop(o),s) → carrying(o,s)
The special function
do
causes an action to be performed
and move from one situation to another:
do(a,s) → s'
Effects of an action are written as
Poss(a(o), s) ∧ P(o, s) → F(o, do(a(o),s))
Example:
Poss(drop(o),s) ∧ fragile(o) → broken(o,do(drop(o),s))
Axiom:
do(a,s)=do(a',s') only if a=a' ∧ s=s'
No persistence axiom, rather frame axioms for each action.
Poss(a,s) ∧ ϒ
F
+
(x,a,s) → F(x,do(a,s))
and/or
Poss(a,s) ∧ ϒ
F
-
(x,a,s) → ∼F(x,do(a,s))
©2012
Charles Petrie
- permission to reproduce widely with attribution.
