On 8/3/2011 1:24 AM, doug foxvog wrote:
> I suggest that a plan is something in between these two positions. The
> Goal could be considered not to be "part" of the Plan, but an organizing
> principle for the Plan. However, the Plan would be a proposed method of
> achieving the Goal (through instantiating a set of Action types with a
> specific (partial) ordering), and not a set of Actions. The intent is
> NOT to engage in specific Actions, but to engage in Actions that meet
> constraints of the plan (including inter-action temporal constraints). (01)
I'm reluctant to turn a common English word into a technical term
that excludes the primary meaning of the word. (02)
Note that physics adopted common words, such as 'force', 'energy',
'power', and 'work', as technical terms. But each of the technical
meanings falls within the informal range of meanings. (03)
The original meaning of 'plan' was "a drawing on a plane", and it's
still one of the most common meanings. Furthermore, a declarative
specification of a plan starts with just two parts: (04)
1. Preconditions: resources, budgets, personnel, etc. (05)
2. Postconditions: goal to be achieved. (06)
The planning process fills the gap between #1 and #2 with subgoals
for intermediate steps that could be specified either by procedures
(sequences of action types) or by declarations with their own
preconditions and postconditions (i.e., subgoals). (07)
The goal is the starting point of any planning process, and its
achievement is the criterion for judging success or failure. If
you need a term for the intermediate steps, the obvious choice is (08)
'the intermediate steps of a plan'. (09)
Each step could be specified by a procedure or by a declaration.
But many intermediate steps might not be fully determined until
the time of execution -- and many of them may be changed during
the execution. But the goal is the most constant part. (010)
> The constraints include the type of action (such as turning left at a
> specific intersection instead of breaking an egg) as well as spatial,
> temporal, and inter-action constraints. (011)
Some plans might not specify any action types. For example, a plan
could consist of a line drawn on a road map, and the driver would
have to decide what action to take at each intersection. A left
turn on the map might require a right turn at a cloverleaf. (012)
> ... the possible world of the plan is a loosely
> constrained future world with much unspecified. The actual 4D world that
> we inhabit (or 3D world that we WILL inhabit) has infinitely more content
> (more facts are instantiated) than the possible world of the plan. (013)
Yes. That's why it is extremely misleading to say that a plan consists
of actions or action types. Many plans don't specify any actions. (014)
> MW & JS are merely using different definitions of the word "constraints"
> here. JS is not referring to linear programming constraints. (015)
Yes. That's what I was trying to say. I often say 'constraint' instead
of 'axiom' because the word 'axiom' tends to scare non-mathematicians. (016)
> A Method may be more generic than a Plan. (017)
Yes. The dictionaries say that a plan can be "a method" with
additional qualifications. (018)
> I don't understand how the definition of "plan" can be the *execution*
> of a method, which i understand to mean a single complex event. (019)
I agree. (020)
John (021)
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