Re: A different definition of MINUS, Part 3

From: Bob Badour <>
Date: Sat, 20 Dec 2008 18:35:36 -0400
Message-ID: <494d733a$0$5478$>

paul c wrote:

> Cimode wrote:
> ...

>> There are a lot of problems related to deriving a language definition
>> directly from traditional algebra, one of them being determining a
>> semantics that maps to RL traditional formalism in an exhaustive
>> fashion, while remaining effective to be expressed semantically by a
>> programmer.  Since defining a language does not answer the same
>> problem than establishing a theorem, it is difficult for me to imagine
>> they could both be similar solutions.
>> ...

> I think those are profound observations. I imagine it is easy for a
> designer to fall into the trap of designing a language for the algebra
> instead of designing a language for the purposes in mind. For example,
> Codd wrote very little about his calculus and algebra per se compared to
> everything else. From the get-go, he had various operators called JOIN.
> For all I know, he did not think his join was defined by the TD join
> and so not by the A-algebra A <AND> B definition. We all must die and
> of course I don't like the idea but in his case we all have an especial
> reason to be sorry he is dead. I met him once, just as his book was
> coming out, but I was so completely ignorant about the relationship of
> the calculus to the algebra that I didn't think to ask him any questions
> about that. Although I knew a bit of the calculus, I hadn't made the
> algebra connection and the standard advice I gave to journeymen Cobol
> programmers and such was very crude, having to do with I then called
> 'regular' sentences. Strangely enough, people whose native languages
> wasn't English seemed to me to do better with this advice than the
> native speakers.

Dijkstra wrote an EWD where he explained why programming in a second language has advantages. Received on Sat Dec 20 2008 - 23:35:36 CET

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