From: Tom Cloyd <tomcloyd@...>
Date: 2008-12-24T04:21:13+09:00
Subject: Re: Name that data structure!


Ian Hobson wrote:
> Tom Cloyd wrote:
>>
>>
>> I now can specify node relationships. Some examples:
>>
>> .n Tom .r is a .n poor programmer
>> .n apple r. is not .n bridge building material
>> .n e=mc**2 .r could be .n true
>>
>> Obviously, these aren't sentences, so we do not use articles, 
>> conjunctions, and the like.
>>
> Hi Tom,
>
> What you have described is the associative model of data (storage).
>
> Each association is three things
>    A subject
>    The association (almost verb, but more accurately copula) such as 
> "is a", "sells", "knows programming language" etc
>    An Object 
> The subject and object can be either entities (real things) or an 
> association. Thus
>
>   ((Ian, isa Person),  Drives,  (Vehicle, RegNo, AB54CDE))
>
> The great strength is the distinction between entity (e.g. people, 
> legal entities, cars), and their relationships (supplier, customer, 
> drives etc).
> An entity has a life span and could be destroyed. When it ceases to 
> exist all relationships into which it entered, become void. 
> Relationships usually have start and end times.
>
> Another feature is the implied inverse of the relationship. If I drive 
> a car, that car is driven by me.
>
> So instead of a computer system having a suppliers database, a 
> customers database and an employees database, it has a database 
> containing "legal entities" and "people" who may have "supplier", 
> "employee" or "customer" relationship with the company. (There should 
> be no legal entities as employees - that is a data error). Clearly a 
> supplier or employee could also be a customer, and it is not unknown 
> for an employee to be an occasional supplier for one-off items.
>
> Most accounts departments spend a lot of time sorting out problems 
> with customers who are also suppliers. Now they are easy to handle.
>
> Note the unusual nature of an address change. I and where I live are 
> entities, with a "lives at" relationship between them. To alter where 
> I live, the system must creates a new address and alters my "live at" 
> relationship (dated when I move).
>
> See if you can get hold of a copy of "The associative model of data" 
> by Simon Williams (ISBN 1-903453-00-3).  Lazy Software (William's 
> company) are the publishers and gave away copies many years ago for 
> marketing purposes. They may still have copies. It contains a very 
> clear explanation of the what and how, and describes a general purpose 
> user interface for editing such structures.
>
> I have long felt a PIM based on these principles (with some form of 
> schema definition language on top), would be a very powerful and 
> flexible tool.
>
> Regards
>
> Ian
>
>
>
>
>
Wow. Ian, this is my holiday gift - from you. I got to this model from 
several diverse sources, but a major one was simply me- working things 
out with sketches made on sheet after sheet of blank paper. It's been a 
lot of run, and considerably exciting. I really did think I was on to 
something, if only because I recognized strong similarities to how 
organic data processing works.

Your orienting me to previous work done with these concepts is simply 
terrific. I strongly suspected there were other people I should be 
reading. You given me a real lead in that direction.

I absolutely will continue working on this - I'm learning too much Ruby 
not to. But I also want to USE the darned thing, and in fact already am.

Thanks again for taking time to share your knowledge!

Tom

-- 

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Tom Cloyd, MS MA, LMHC - Private practice Psychotherapist
Bellingham, Washington, U.S.A: (360) 920-1226
<< tc@tomcloyd.com >> (email)
<< TomCloyd.com >> (website) 
<< sleightmind.wordpress.com >> (mental health weblog)
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