Re: computational model of transactions

"David Cressey" <dcressey_at_verizon.net> wrote in message news:hI_Ag.2736$z12.866_at_trndny02...
>
> "Brian Selzer" <brian_at_selzer-software.com> wrote in message
> news:AKTAg.1198$1f6.1097_at_newssvr27.news.prodigy.net...
>>
>> "J M Davitt" <jdavitt_at_aeneas.net> wrote in message
>> news:FDSAg.63277$Eh1.44696_at_tornado.ohiordc.rr.com...
>
>> > I think GW triggered on *always* in the phrase, "Axioms are always
>> > true..." In this world, axioms are little more than things that
>> > are said to be true because someone says they're true and we
>> > sometimes encounter axioms which contradict each other.
>>
>> Thank you for pointing that out. I didn't intend that sense of the word;
>> though, now that you mention it, I can see how that could be assumed.
> What
>> I did intend was the sense denoting a fundamental, self-evident truth
>> that
>> is so obviously true that a counter-proof would be inconceivable.
>>
>>
>
> I'm going to recall a discussion some months ago, about whether what is
> stored in the database is "fact" or "opinion".
> A given assertion could be axiomatic within the contrived world of the
> database, but easily proven false in the real world.
>

I understand what you're trying to say, but that wasn't how I was using the term. It is always the case that there are differences between the real world and the world of the database because the world of the database contains at best only a subset of the real world and may, as you've stated, be contrived. Worse, the truth of the propositions in a database are only as reliable as the perception and accuracy of the people that provided the information, and as anybody who's been at the scene of an accident knows, one person's perception can deviate significantly from another's. The point I was trying to make was based on the idea that there can only be two types of propositions in a database: (1) propositions that are invariably true, that is, whose truth is guaranteed not to change regardless of any circumstance that may arise in the world of the database; and (2) propositions whose truth depended on the state of the world of the database that was current at the point of the last update.

> Illustration:
>
> Teller (looking at screen): According to my database, you're dead.
> Client (exasperated): But, as you can see, I'm not dead!
> Teller: I'm sorry, but I won't be able to help you until someone back at
> headquarters fixes the database.
> Client: Is there someone else I can speak to?
>
> Just as a side note, an interesting thing is going to occur back at HQ.
> After verifying that the database is in error, some DBA is going to go in
> with a manual update, and alter the state of the database to make it
> agree
> with reality.
>
> At some level of abstraction, the transaction log is going to look like a
> client died, and at a later time rose from the dead. But you and I know
> that an error was originally recorded in the DB, and later corrected by a
> transaction. The history of opinion doesn't follow the same trajectory as
> the history of fact.
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Received on Sat Aug 05 2006 - 18:37:24 CEST