Re: RM and abstract syntax trees

From: Bob Badour <>
Date: Tue, 30 Oct 2007 15:13:16 -0300
Message-ID: <4727743d$0$14874$>

paul c wrote:

> David BL wrote:

>> On Oct 30, 6:29 pm, "Roy Hann" <specia..._at_processed.almost.meat>
>> wrote:
>>> "David BL" <> wrote in message
>>>> In the following I compare different techniques for representing an
>>>> Abstract Syntax Tree (AST), concluding that RM is poorly suited.
>>> [snip]
>>>> I anticipate that this rule of thumb provides a useful insight on that
>>>> rather vague notion of "semi-structured data".  ie it explains exactly
>>>> when and why there is data that is not suitable for direct
>>>> representation in RM.
>>> Education triumphs over learning once again.
>>> Roy
>> Please say what you disagree with.  I can take it.

> Okay, from your original post:
> "So RM is forced
> to expose the equivalent of pointers directly in the representation.
> Furthermore, the RM has no mechanism for hiding these pointers or
> giving the user an interface that promotes the idea that a node
> logically represents a value."
> Where does RM ever mention pointers? Eg., What are the pointer
> operations that RM supports?
> (ps: I don't agree that RM can't represent nested lists but I would
> agree that it's not much fun to manipulate them, I wish Codd had said
> more about nested relations as I have a feeling he spent some time
> considering them.)

It seems he considered them unecessary in the sense one can always normalize the data to obviate the need for them. Received on Tue Oct 30 2007 - 19:13:16 CET

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