Re: Using the RM for ADTs

Brian Selzer wrote:

>
> "David BL" <davidbl_at_iinet.net.au> wrote in message
> news:095c8b9d-eb68-4a39-acdf-942d5db07b2e_at_y10g2000prf.googlegroups.com...
>> On Jul 3, 12:58 pm, "Brian Selzer" <br..._at_selzer-software.com> wrote:
>>> "David BL" <davi..._at_iinet.net.au> wrote in message
>>
>>
>>> > Consider a node to which n components are connected and n is large.
>>> > Using pairwise connections can either be exceedingly arbitrary (by
>>> > only representing n-1 pairs) or it makes for enormous redundancy (by
>>> > representing all n(n-1)/2 pairs).
>>>
>>> > I think this is much worse that the symmetry problem with resistors.
>>>
>>> I see your point, but I still think that assigning components artificial
>>> identifiers is better: the unordered pairs could be replaced with or
>>> preprocessed into a single set per node prior to the determination of
>>> isomorphism. For example,
>>>
>>> {resistor1:lead1,capacitor2:lead1,transistor1:lead2}
>>>
>>> discribes a node that connects a resistor and a capacitor to the base of
>>> a
>>> transistor.
>>>
>>> The above contains the same information as the unordered pairs
>>>
>>> {{resistor1:lead1,capacitor2:lead1},
>>> {resistor1:lead1,transistor1:lead2}}
>>>
>>> without either the arbitrariness or the redundancy you seek to avoid.
>>
>> I cannot tell which approach is better. Anyway, the point I find
>> interesting is that in both cases nesting can ensure the schema meets
>> the given requirements for logical equivalence of circuit values.
>
> I think that this is the perfect counterexample to some of the myths that
> are perpetuated here on cdt. It illustrates valid uses of both artificial
> identifiers and nesting. I think one would be hard pressed to come up with
> a solution that doesn't involve the use of artificial identifiers. The
> nesting can, of course, be dispensed with through the introduction of
> additional artificial identifiers.

I think it is a perfect example of wondering why chisels don't make good screwdrivers.

-- 
Roy