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Self-watching II: Could the trace and the stream be merged? December 11, 2006

Posted by amahabal in Uncategorized.
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In my last post I mentioned how I think Metacat’s temporal trace did not get it exactly right when it allowed important but ancient events to be accessible without also allowing recent events just below the importance threshold to be accessible. I just realized that the stream of thought in Seqsee makes the exact opposite error: it remembers the most recent thoughts but not important thoughts that are somewhat old.

 

Let me review briefly how the stream of thought currently works. After that I will be able to explain what I am thinking would be required to merge both views.

 

Seqsee contains “thoughts”, which could be looked at as codelets that are handled in a special way. When a thought is “the current thought”, its fringe is calculated. The fringe contains things related to the current thought. More on this later at some point but suffice it to say for now that if the fringes of two thoughts overlap then they might be similar in some way. A concrete example would help: the groups [2 3 4] and [7 8 9 10] may both have “ascending” in their fringe. Overlapping fringes is the primary method by which similarity discovery happens in Seqsee.

 

Another thing that the “current thought” does is to suggest potential actions to be taken. For instance, if the current thought is about a group [2 3 4] then a possible suggested action could be “try to make the group longer”.

 

The stream remembers the last few thoughts and their fringes. The most recent thought’s fringe is present to the greatest extent. Currently, the stream only remembers the last 10 thoughts. The stream then checks the fringe of the current thought for overlap with the stored fringes. If a significant overlap is discovered with a prior thought then a codelet is launched to explore whether the two are related (thus possibly precipitating a bond formation).

 

In Seqsee, this overlap was looked at A Good Thing. After all, uniformity is a good thing. Finally, we want to discover a rule that explains the sequence harmoniously and is itself simple. Therefore, Seqsee currently tries to make the most of the good news that overlap happened by responding with attempted bond formation. However, fringe overlap can also signals problems. If you are having the same thought over and over and over again, the fringes will, of course, overlap.

 

The temporal trace is sensitive to the repetition of certain types of events. There are codelets that try to find patterns amongst snags that the program hit. If snags were one type of thought in Seqsee then a new snag— if it was similar to another recent snag— would awaken Seqsee to this snag repetition. Unlike groups with overlapping fringes, snags with overlapping fringes are bad news and Seqsee can take corrective action.

 

This does not yet I mean that the stream of thought can take over all the work that the temporal trace did. The trace also remembered the order of events and that has not yet been integrated into the stream. However, whether (and how much) we remember the order of events is not clear to me. I remember several conversations with two friends at different times. While I have some sense of the ordering of conversations with the first friend (i.e., I have some sense of which conversation which conversation happened before which), and also some sense of ordering of the conversations with the second friend, I cannot at all re-create temporally the set containing both sets of conversations: I cannot say if this conversation with the first friend happened before or after that conversation with the second friend. I suspect that the ordering I could remember within each individual set was something that I calculated (figured out) instead of really remembering. I remember Roger Schank talking of something similar in his book “dynamic memory”.

 

The previous paragraph notwithstanding, we do remember some amount of ordering information, I think, and the stream needs to be able to do that at least a little bit. I also need a way to remember important but old thoughts.

 

I think I am happy with the way things are going with this “integration”. I am curious to see how the story unfolds!

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