1. Representation of Actions in Cyc and KM
RKF PI Meeting Thursday, October 18, 2001
Aarati Parmar
FRG Stanford
Pierluigi Miraglia
Cycorp
9/19/2018
Formal Reasoning Group, Stanford University

2. Representation of Actions in Cyc & KM
Cyc and KM (Component Library v1.0) are both logic-based ontologies with inheritance, and some non-monotonic reasoning.
Compare on:
Basic Temporal Formalism
Action Ontology
Reasoning about Change
9/19/2018
Formal Reasoning Group, Stanford University

3. Basic Temporal Formalism: States
Basic unit of state is implemented as a microtheory/context in both:
States are nested, so that facts from all super-states are visible
One unique super-situation (BaseKB/*Global) housing timeless facts, visible to all situations.
Cyc's holdsIn and ist-Asserted corresponds to KM's holds-in, in-situation
BaseKb/
*Global s F s’ F
9/19/2018
Formal Reasoning Group, Stanford University

4. Basic Temporal Formalism: States
KM uses situations of sitcalc (state space):
Cyc has two temporal formalisms:
1. “Davidsonian” framework
Action sentences are implicit existential assertions
Instances of Events (subclass of Situation- Temporal) have spatio-temporal extent
Slots and temporal relations (ActorSlots; startsAfterEndingOf) relate properties of actions
2. In development:
Assertions modified by temporal and modal operators
(possible-Historical (eats Fritz Caviar)) s F a s’
9/19/2018
Formal Reasoning Group, Stanford University

5. Basic Temporal Formalism: Actions
In both, actions are defined as events with a protagonist.
KM actions connect situations.
Has next-situation = result of sitcalc (can represent possible futures:
Actions can be composed of subactions, etc.
Future support for situation during the action.
Cyc actions more process-like, (instances of Event have temporal extent.)
9/19/2018
Formal Reasoning Group, Stanford University

6. Formal Reasoning Group, Stanford University
Action Ontology
Action properties inherited in both Cyc and KM through hierarchy
KM:
uses slots and values for arbitrary properties
more powerful than most frame-based languages as values can be evaluable expressions containing quantification and implication:
precondition list for Move:
(if (has-value (the source of Self))
then (forall (the object of Self))
(:triple It location (the source of Self)))
9/19/2018
Formal Reasoning Group, Stanford University

7. Formal Reasoning Group, Stanford University
Action Ontology
Cyc:
properties formalized through Roles, ActorSlots other temporal relations
employs "skolem functions" to relate objects to actions, e.g. (relationAllExists buyer Buying IntelligentAgent)
how an action is done formalized through performanceLevel, rateofEvent
also categorizes different temporal objects (AccomplishmentType (actions that have a completion point), etc.)
9/19/2018
Formal Reasoning Group, Stanford University

8. Reasoning about change: Preconditions
To do progression (regression), preconditions, as well as the result of an action need to be formalized.
KM uses STRIPS prec, add, delete lists to compute effects of actions.
Cyc has an expressively rich set of preconditions, but they are not uniformly used (what predicate do we query to see if action a executable?).
9/19/2018
Formal Reasoning Group, Stanford University

9. Reasoning about change: Preconditions
Cyc preconditions represented through a multitude of predicates:
some ActorSlots are specific preconditions (inputs)
preconditionFor-{PropSit, Events, Props, SitProp}
(preSituation Event1 StaticSit2) a very weak kind of precondition
necessary conditions necConditionFor- Event and necConditionFor-Scene
9/19/2018
Formal Reasoning Group, Stanford University

10. Reasoning about change: Results
KM:
STRIPS lists compute direct effect of actions
a simple form of non-monotonic reasoning used to compute the inertial effects
extra support for ramifications (non-inertial effects)
9/19/2018
Formal Reasoning Group, Stanford University

11. Reasoning about change: Results
Cyc:
(postSituation Event1 StaticSituation2) : closest thing to result
causation between other/more general classes: eventOutcomes, causes-EventEvent, causes-SitProp, causes-ThingProp, causes-PropProp
looser notion of salience: postEvents and inReactionTo, and functions STIB, STIF.
Once again, a plethora of different levels of result used in Cyc, but no one used generally.
9/19/2018
Formal Reasoning Group, Stanford University

12. Formal Reasoning Group, Stanford University
Conclusions
Cyc has a rich ontology, but current formalism does not go the route of talking about the set of facts which change, like KM.
KM is better qualified to infer the results of actions, for this reason, as well as the non- monotonicity built into the system.
While Cyc can teach us much about actions and properties of them, KM can actually simulate these actions.
9/19/2018
Formal Reasoning Group, Stanford University

13. Formal Reasoning Group, Stanford University
Bibliography
Clark, P. and Porter, B. (1998). KM (v1.3): Users Manual. Knowledge-Based Systems Group, Univ. of Texas at Austin, Austin, Texas.
Cyc.
McCarthy, J. and Hayes, P. J. (1969). Some Philosophical Problems from the Standpoint of Artificial Intelligence. In Meltzer, B. and Michie, D., editors, Machine Intelligence 4, pages Edinburgh University Press.
9/19/2018
Formal Reasoning Group, Stanford University