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

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

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

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

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

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

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

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

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

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

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

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

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. http://www.cyc.com. 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 463--502. Edinburgh University Press. 9/19/2018 Formal Reasoning Group, Stanford University