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- Comments: Gated by NETNEWS@AUVM.AMERICAN.EDU
- Path: sparky!uunet!paladin.american.edu!auvm!BEN.DCIEM.DND.CA!CDLOVE
- Message-ID: <9209141743.AA04398@ben.dciem.dnd.ca>
- Newsgroups: bit.listserv.csg-l
- Date: Mon, 14 Sep 1992 13:43:21 EDT
- Sender: "Control Systems Group Network (CSGnet)" <CSG-L@UIUCVMD.BITNET>
- From: Chris Love see mmt <cdlove@BEN.DCIEM.DND.CA>
- Subject: Imagination construction!
- Lines: 132
-
- [From: Chris Love (920914.1300)]
- [To: Bill Powers (920910) and Rick Marken (920910)]
-
- Thanks for the encouraging posts!
- Bill, I have already started working on this *new* model. And
- I don't know either when it will be complete, but I can't see
- it taking too long (< 1 month) since all the *control objects*
- have already been created, such as linking objects, connection
- routines, the basic ECS object, etc.. But in development work,
- as I'm sure your aware this is never a sure thing!
-
- >Perhaps what you feel is missing is the pairing up. In fact, it's
- still there...
-
- I see Bill. This really does appear that, for the purpose of that
- n-level ECS, it is imagining without even knowing it. Kind of like
- drifting in the middle of a lecture - it's nor until you bring
- yourself back to attention (reality) that you realize you ever left!
- I say this because that n-level ECS is being provided all information
- in a regular manner as if nothing unusual was happening to it,
- although the information (percepts) are really imagined ones.
-
- The problem: By allowing those n-1 level ECS' to provide the
- imagined percepts to your (focus) n-level ECS you are getting
- (undesired?) influence from neighboring n-level ECS'?
-
- How? This is occuring because those n-1 level ECS' are also
- receiving outputs from the neighboring n-level ECS' in the
- process of generating the net input refernce sum.
-
- Do you want this? If you wish to evaluate the effectiveness of
- that n-level ECS, I think not since you now have external
- uncontrollable influence from neighboring n-level ECS' through
- an indirect path. If this was your intention then I do not
- understand the reason, or possibly overlooking something. Please
- explain.
-
- In my proposal, you short circuit the ECS that you want in
- imagination mode. No influence from neighboring n-level ECS'
- occurs. I know it does in the *global* sense through the
- environment **eventually** as recieved refernces, but this is
- far enough removed, I feel, to be of little effect. When that
- n-level ECS imagines you want it to try to perceive doing well,
- that's the objective, right? So, in achieving, or attempting to
- achieve this objective we must vary it's direct weights in relation
- to it's imagined percepts such that it reduces its error. THis
- results, of course, in a better controller. THis is my hypothesis.
-
- Bill, if you removed the influence of those other n-level ECS'
- contributions to those other n-1 level ECS refernce sums then I
- think we have agreement on the imagination objectives.
-
- >I'll be interested in your implementation of an imagination loop
- that can adjust perceptual weights...
-
- Me too! I'm open to any suggestions. My baseline proposal is to
- use some form of Hebbian stlye learning (also known as the Widrow-
- hoff rule). As applied to
- PCT it goes something as follows:
- Delta weight = learning rate* connection wt. * error signal
- New wt. = Old wt. + Delta wt.
-
- Comments:
- The learning rate is typically set to a small value between
- 0.1 and 0.3.
- The connection weight is the exisiting weight (wt.) of the
- connection of interest.
- The error signal is that signal eminating from the comparator.
-
- What does this do?
- Well, as I see it it correlates particular references with
- particular percept signals. In wording the Hebbian rule says
- something like, "... if two connecting units are correlated
- then strengthen that connection." THislowers the threshold
- necessary to *fire* that receiving unit in the future under
- similar circumstances.
-
- Is this the right thing to do?
- That depends on wether their is correlation between the refernces
- an the percepts? And whether this correlation is desireable to
- learn, i.e., will it make controlling better?
-
- If anyone has any comments, improvements, either to prove or
- disprove the above proposal or anything else - great! Let's have
- at 'em!
-
- ------------------------------------------------------------
- Rick Marken-
- >Whatever throws the switch must have reason for doing it...
- >the reason is to control something.
-
- >... it would be nice to have a system that alters the imagination
- connections through the perceptual and output system...
-
- >the imagination swithch is probably the output of a control system..
-
- Sounds good to me too Rick.
- I also thought that another possibility would be to allow the
- ECS to detemine that it needs to imagine. THis would happen, like
- me, when I work too hard and get (temporarily) *brain dead* and
- my mind automatically swithches to imagination mode to try to
- solve *the problem*, I guess subconciously.
-
- When I say "allow the ECS to determine", I should specify that
- the *swithch* is internal rather than coming externally from
- another ECS. I would like to avoid this path of exploration
- first if i can since it requires, i feel, a dedication to
- function, i.e., that ECS' objective is to *only* know when to
- send a *swithch to imagination* signal to other ECS'. I, as
- a designer, now have to worry about how to make such an ECS do
- just that. I would prefer to develop, if i can, a *almighty*
- ECS that is VERY GENERIC in the sense that everything that must
- happen in an ECS or to an ECS can be handled *EXCLUSIVELY* by
- that ECS. It does not require outside influence to make decisions
- on what its actions should be.
-
- As an engineer, if it turns out that your proposal works ok,
- great I'll implement it tommorow. I'm in no way biased to either
- approach - just one that works and is reliable, reproduceable,
- and expalainable (is that a word?)!!! I think at this point,
- however, that the almight ECS may be the way to go. What do you
- think about this?
-
- >figure out how to do experiments that would guide the modelling
- of imagination...
-
- I can't imagine these expts. now either but you can't always see
- the end of the tunnel; you just have to beleive that it will appear
- before you drop!
-
- Thanks,
- Chris. (DCIEM)
-