In the AI planning community, typically there are 3 phases of "planning", i.e,
1) planning
The result of the planning phase is a plan (or plans) which then gets
instantiated, i.e., concretized into a specific tree/graph task representation,
where the tasks and subtasks are either logically (or, and, not, etc.) or
temporally related (sequential, parallel, etc.), with pre-conditions (think of
constraints on the tasks, their operations, or resulting values) and
post-conditions (similarly, constraints).
2) scheduling
3) execution. (01)
Each of these phases have pre-conditions and post-conditions. One might look
at the example of OWL-S as a kind of reactive planning paradigm applied to
semantic web services. There are other planning languages such as the Planning
Domain Definition Language (PDDL):
http://ipc.informatik.uni-freiburg.de/PddlResources; the old STRIPS; Core Plan
Representation, etc.; for other info, see:
http://en.wikipedia.org/wiki/Automated_planning_and_scheduling;
http://www4.ncsu.edu/~stamant/planning-resources.html. (02)
You might look at Dan Nau's slides on automated planning:
http://www.cs.umd.edu/~nau/planning/slides/. His first chapter takes you
through multiple definitions of plan. (03)
Thanks,
Leo (04)
-----Original Message-----
From: ontolog-forum-bounces@xxxxxxxxxxxxxxxx
[mailto:ontolog-forum-bounces@xxxxxxxxxxxxxxxx] On Behalf Of doug foxvog
Sent: Thursday, August 04, 2011 3:14 PM
To: [ontolog-forum]
Subject: Re: [ontolog-forum] intangibles (was RE: Why most classifications are
fuzzy) (05)
On Wed, August 3, 2011 15:20, Matthew West said:
> John Sowa said:
>> .... (06)
>> But I disagree that "a plan is a set of actions". Whether you're
>> using a 4D analysis or 3+1D is irrelevant to the definition of 'plan'. (07)
> MW: Well I spent 30 years working for Shell, an organization that lived
> and thrived by creating plans and then executing them.
> My usage is just how I found the word being used there. (08)
I would suggest that even at Shell, a plan is a structured set of action
templates, not a set of fully pre-described actions. (09)
>> As I suggest to anybody who works on knowledge representation or
>> ontology, consult a good dictionary for a neutral (i.e., non-dogmatic,
>> not theory laden) opinion about the way words are commonly used.
>>
>> For example, the Merriam-Webster 9th Collegiate Dictionary says
>> that the word 'plan' comes from the same Latin root as the word
>> 'plane'. That origin leads to MW definition #1:
>>
>> > 1. a drawing or diagram drawn on a plane.
> ...
>> > 2c. a detailed formulation of a program of action
>
> MW: It is this last that corresponds to the usage I am referring to. So
> therefore not to any of the others, which are distinct. (010)
But speaking carefully, a "program of action" is not a set of actions,
but an organization of action types. Not only is there a difference
between actions, which are concrete events and types of action; the
program of action can have temporal and other dependencies, while a
mere set does not have such relationships among set members. (011)
> The plan of a building for instance is an entirely different
> sort of thing (and is as
> likely to be of building after it was built as before).
> ...
>> All these definitions say that a plan is a goal or a method.
>
> MW: Not so. (012)
The first definition of plan (the building plan) need not be either.
It may merely be post hoc as MW states above. (013)
>> None of them identify a plan with the sequence of actions.
>
> MW: See 2c "a program of action" is just that. (014)
The program may not be just a linear sequence. And what are
positioned in the program is action types, not action. (015)
>> If you prefer a British view, following are the four senses
>> of 'plan' in the Longman Dictionary of Contemporary English:
>>
>> > 1. a (carefully considered) arrangement for carrying out
>> > some future activity.
>
> MW: This is near enough the sense I mean.
> ...
>> Both dictionaries emphasize the goal (or a drawing of the goal)
>> and the intentions that led to the goal: a plan "always implies
>> mental formulation", and the arrangement is "carefully considered".
>
> MW: Of course.
>>
>> > MW: A sequence of action (types) is a method, but not a plan.
>> > A plan may be a particular execution of a method (but not
>> > necessarily).
>>
>> Please note that both dictionaries define a plan as either
>> a goal or a method for achieving the goal. I have never
>> heard anybody use the word 'plan' in the way you describe.
>
> MW: I suggest you both re-read what you have posted and talk to some
> people who do project management for a living. (016)
I have certainly heard people in project management discuss plans which
haven't been completed yet. (017)
-- doug f (018)
> ...
>> Another comment about word usage:
>>
>> > JFS: The specifications of the plan could be called axioms,
>> > constraints, or laws.
>> >
>> > MW: No. What is often the case is that the constraints
>> > (resource availability, time, materials) are inputs to
>> > formulating a feasible plan (I think of linear programming
>> > in the oil industry). However, the constraints are not
>> > the plan itself.
>>
>> My primary word was 'specifications'. They determine the methods
>> the dictionaries mention. There are two ways to specify a method:
>>
>> 1. Procedural: An ordered sequence of imperative commands,
>> as in a typical programming language.
>>
>> 2. Declarative: A set of propositions that state the starting
>> conditions (prerequisites) and ending conditions (desired
>> goal) for any procedure that implements the method.
>>
>> A procedural specification is useful for efficient execution
>> by a specific machine or by a human agent who is not expected
>> to innovate or to deviate from a fixed sequence.
>>
>> A declarative specification is more general, since it covers
>> an open-ended variety of procedures that begin with the starting
>> conditions and end with the desired goal. It allows greater
>> flexibility in changing the order of execution and adapting
>> to unforeseen circumstances. But it does require a more
>> intelligent machine or human.
>>
>> I used the words 'axioms', 'constraints', or 'laws' for the
>> propositions that state the preconditions and postconditions
>> of a declarative specification. I am happy to replace those
>> words with any other way of talking about the propositions.
>>
>> I'll admit that people rarely use the terminology of logicians
>> or computer scientists to talk about their planning sessions.
>> But you can analyze their informal discussions and classify
>> their ways of describing plans as procedural, declarative,
>> or some informal mixture of both.
>
> MW: I've spent enough of my working life doing planning that I know full
> well that you have not produced a plan that anyone will accept as such
> when
> you have done no more than state the boundary conditions. Only when you
> have
> produced a solution that satisfies those boundary conditions do you have
> something a budget holder would sign of as a plan.
>
> Regards
>
> Matthew West
> Information Junction
> Tel: +44 1489 880185
> Mobile: +44 750 3385279
> Skype: dr.matthew.west
> matthew.west@xxxxxxxxxxxxxxxxxxxxxxxxx
> http://www.informationjunction.co.uk/
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>
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"I speak as an American to the leaders of my own nation. The great
initiative in this war is ours. The initiative to stop it must be ours."
- Dr. Martin Luther King Jr.
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