DARPA Rome Lab. Planning Initiative
SPAR - Sentences

This is a more detailed discussion of the SPAR issue 32, "Modification to KRSL-Plans 20-Sep-96 Definition in 15 Sentences".

Current working version


General Comments

KM stated: Some of these terms should perhaps be defined more explicitly (OBJECTIVE, WORLD-STATE). Others should simply be declared as primitive concepts for the sentence framework -- perhaps an explicit listing of those terms could be inserted prior to the presentation of the sentences.


SPAR Core Sentences

C.1. A PLAN relates an ACTIVITY-SPECIFICATION and one or more OBJECTIVES.

C.2 An ACTIVITY-SPECIFICATION denotes or describes zero or more ACTIVITIES.

C.3 An ACTIVITY-SPECIFICATION may include relationships between those ACTIVITIES and ACTIVITY-RELATABLE-OBJECTS (AROs).

C.4. EXECUTION of an ACTIVITY may change the WORLD-STATE.

C.5. An AGENT is an ACTIVITY-RELATABLE-OBJECT which can PERFORM ACTIVITIES and/or HOLD OBJECTIVES.

C.6. An ACTIVITY takes place over a TIME-INTERVAL identified by its two ends, the BEGIN-TIME-POINT and the END-TIME-POINT.


SPAR Extension 1 - Additional Terminology

The following sentences extend the core sentences above to provide additional terminology.

E1.1. An ACTION is an ACTIVITY which has or could have (in the domain model) an ACTOR.

E1.2. An EVENT is an ACTIVITY which does not have and could not have (in the domain model) an ACTOR.

E1.3. An ACTOR is an AGENT which is the motive force behind an ACTIVITY.

E1.4. A RESOURCE is an ACTIVITY-RELATABLE-OBJECT which is USED, MODIFIED, CONSUMED or DESTROYED during the EXECUTION of an ACTIVITY.

AT stated: Can I suggest the addition of a sentence after E1.4, meaning that the ones that follow need to be renumbered.

E1.5 A SUB-ACTIVITY of an ACTIVITY is an ACTIVITY included in an ACTIVITY-SPECIFICATION of the parent ACTIVITY.

E1.6 A PROCESS is an ACTIVITY whose ACTIVITY-SPECIFICATION includes more than one SUB-ACTIVITY.

E1.7 A PRIMITIVE-ACTIVITY is an ACTIVITY whose ACTIVITY-SPECIFICATION includes no SUB-ACTIVITY to the level detailed in the model.


SPAR Extension 2 - World State

KM stated: There is a World in which planning and plan execution takes place (I actually think that Environment is a better term, since it doesn't imply a 'global' scope). A particular snaphsot of the world at a given point in time is called a World-State. A WORLD-MODEL constitutes a description of the World (note though, that this description need not be complete or accurate wrt the actual World). A WORLD-STATE-DESCRIPTION describes an actual/expected/hypothetical World-State.

KM Stated: Here is an attempt to compile a set of sentences that capture the relevant details (perhaps (1) and (2) should simply be `background material' rather than sentences, since they really contribute to defining the background framework for SPAR).

  1. A PLAN is designed for and (possibly) executed within a specified World (Environment).
  2. A particular snaphsot of the world at a given point in time is called a World-State.
  3. A WORLD-MODEL provides a description of the World (possibly incomplete and/or inaccurate).
  4. A WORLD-STATE-DECRIPTION describes one or more World-States (actual, expected, or hypothetical).

E2.1. A WORLD-STATE-DESCRIPTION partially denotes or describes the WORLD-STATE.


SPAR Extension 3 - Timelines

E3.1. Any TIMEPOINT may be associated with one or more TIMELINES [or CALENDARS?].

E3.2. A TIMELINE [or CALENDAR?] has a nominated begin point and a time unit and may have a nominated end point.


SPAR Extension 4 - Values, Uncertainty and Imprecision

E4.1. A VALUE is associated with each property of each ENTITY.

E4.2. VALUEs may be imprecise.

E4.3. VALUEs may have a PROBABILITY.

E4.4. PROBABILITYs may be subclassed into PROBABILITY-PREDICTION and PROBABILITY-SENSED.

E4.5. A PROBABILITY-PREDICTION is the likelihood of a WORLD-STATE-DESCRIPTION being valid in the future.

E4.6. A PROBABILITY-SENSED is a likelihood that a WORLD-STATE-DESCRIPTION did in fact have the specified value in the past or at the current time.

E4.7. An INFLUENCE-NETWORK is a structure which relates PROBABILITYs and specifies their dependency structure.


SPAR Extension 5 - Conditions and Effects

E5.1. The CONDITIONS of an ACTIVITY are the ACTIVITY-CONSTRAINTs in the ACTIVITY-SPECIFICATION.

E5.2. The EFFECTS of an ACTIVITY are the changes made to the WORLD-STATE by EXECUTION of the ACTIVITY.

E5.3 CONDITIONS which are mutually exclusive may be associated with a PROBABILITY.

E5.4. WORLD-STATE-DESCRIPTIONS which describe changes to the WORLD-STATE may have a PROBABILITY.


SPAR Extension 6 - Evaluations

E6.1. An OBJECTIVE may have one or more EVALUATION-CRITERIA.

E6.2. An EVALUATION-CRITERION may be applied to WORLD-STATE to create an EVALUATION.

E6.3. An EVALUATION may be a predicate (holds/does not hold) or a partial order on the results of [one or more] EVALUATION-CRITERIA.


SPAR Extension 7 - Libraries

E7.1. A PLAN-LIBRARY contains PLANs or portions of PLANs which may be reused in creating new PLANs. A PLAN-LIBRARY has one or more INDEXes which can be used to catalog PLANs and aid in searching for them.

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dept Page maintained by Steve Polyak (Steve_Polyak@ed.ac.uk), Last updated: Fri Apr 28 13:29:23 2000