Re: RM and abstract syntax trees

From: paul c <toledobythesea_at_ooyah.ac>
Date: Tue, 30 Oct 2007 17:46:46 GMT
Message-ID: <a6KVi.160778$1y4.93722_at_pd7urf2no>

David BL wrote:

> On Oct 30, 6:29 pm, "Roy Hann" <specia..._at_processed.almost.meat>
> wrote:

>> "David BL" <davi..._at_iinet.net.au> wrote in message
>>
>> news:1193713604.283167.146850_at_e34g2000pro.googlegroups.com...
>>
>>> 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.) Received on Tue Oct 30 2007 - 18:46:46 CET