2 A Representation for Air Campaign Plan Objectives

The proposed representation for air campaign plan objectives is basically an extension of the present representation used in ACPT. The main goals of the proposed representation:

• To enrich and correct the representation presently used in order to enable automated reasoning (in some degree) about objectives.
• To support error checking during the editing of objectives.
• To serve as a focal-point to think about the elements of objectives in air campaign planning and their representation. For instance, to discuss a representation for objectives as proposed here raises several methodological issues which are important even outside the realm of making systems for supporting air campaign planning.

ACPT currently distinguishes the following components of an objective:

title

This is a textual description of the objective, for example, Disrupt SAM sites in the Changjon region.

measures of merit

This field contains one or more descriptions of success criteria for the objective, for instance, Uncoordinated and delayed Red air attacks.

action

This is a verb, chosen from a menu. There are currently four actions: Attack, Defend, Jam and Monitor.

effect

This is also a verb from a menu with the following choices: Destroy, Attrit, Disrupt and Influence.

location

This is filled (with text) from a list of locations set in ACPT for the scenario or theater at hand.

% complete

A slider allows the user to specify a number between 0 and 100.

review status

This may be either Default, Reviewed or Changed.

parents

This field contains a list of objectives at a higher level to which the current objective is to be considered a child. It is usually filled by selecting one (previously edited) such higher objective.

The representation proposed in this document extends the above representation in order to address two main problems. First, it proposes a more detailed and structured representation for the Title field, that also makes superfluous the fields Effect and Action. Second, it proposes a new field Sequence restrictions, that clears up a difference between prioritization and sequencing which is currently not made and which (according to CHECKMATE) has caused considerable confusion among ACPT users.

2.1 Structuring the Title

The Title field actually contains a statement or specification of the objective -- for instance, Disrupt SAM sites in the Western region. This is presently a free text field in ACPT. The action field and effect fields hint at specifying the desired effect and action types. However, they fall short of specifying the objective in adequate richness of detail. Further, they are filled from a menu of options which is currently extremely minimal and consequently poor.

The proposed representation provides structure to what is currently the title, decomposing it as follows:

action type

This is a verb or verb expression, such as Destroy, Disrupt, Deny use.

action roles

These are descriptions of the objects the action type refers to, in terms of pairs of role name and action object:

role names

are either a preposition (to, from, over) or DOB (symbolyzing the direct object).

role objects

belong to four basic types:

• actions or activities such as production of chemical products or artillery fire in Changjon region.
• action capabilities such as radio transmission capability or ability to conduct ofensive operations.
• objects such as key command centers, SAM radars or electrical power grid.
• aspects such as freedom of navigation or air superiority.
• areas There is only one known example of a goal that uses an area (or location) as an object, which is Drive Red into desired chokepoints and restricted LOCs.

Action objects may also specify who controls or owns the action object (e.g. air superiority OF Blue or production of chemical products OF Red). In more complex descriptions, they may use time and space modifiers similar to the ones used to qualify the whole objective (see below).

modifiers

specify time and space restrictions on the objective, for instance within 21 days, or in Western Black Sea. In other words, they specify the ``when'' and ``where'' of the objective as a whole.

This structure is inspired in case grammars. The basic idea of case grammars is that there is normally a limited number of roles (called thematic or case roles) that an argument of a verb can play with relation to the verb. While case grammars have been dismissed as a general solution for natural language interpretation, they can be an interesting and powerful device in restricted settings such as the one we have in the air campaign planning domain.

The proposed structured representation eliminates the fields action, effect and location of the current ACPT representation.

2.2 Distinguishing Sequence from Priority

ACPT allows the specification of the relative priorities of objectives, which are inherited by their children. If Air Objective O1 has priority over Air Objective O2, the Air Tasks which are specified as their children will also obey that order, i.e. all tasks children of O1 have a higher priority over all tasks children of O2. The priorities may be overridden when the level of targets is reached, i.e. the user may reprioritize any target at his/her will.

While this mechanism has been useful, interviews with CHECKMATE have revealed that users often confuse priority with sequence. In general, the fact that objective O1 has a higher priority than O2 does not mean that it should be executed first. Indeed, if O2 is an objective whose effect is a prerequisite for executing O1, O2 is the one that should be executed first.

We believe that one of the reasons why this confusion exists is because users are currently not allowed to specify that an objective is to be accomplished before (or after, or at the same time than) another. Therefore, we propose to introduce a new field Sequence restrictions, where the user can specify (if known) which objectives are to be accomplished before/after/simultaneous with others.

Further, we have noticed that it is frequently difficult for air campaign planners to make definite sequencing commitments. These commitments have some gradation: sometimes one objective must be accomplished before another is to be pursued, while in other cases it is better but not strictly obligatory to do so. For this reason, we have specified that the three basic sequence relations (before, after and simultaneous with can be modified by one of the following: must, better, better not, must not. These modifiers specify the ``hardness'' or ``certainty'' of the sequence restriction, i.e. how serious they should be taken in the actual sequencing of the objectives and activities later on.