Re: Using the RM for ADTs

From: Roy Hann <specially_at_processed.almost.meat>
Date: Mon, 06 Jul 2009 03:17:13 -0500
Message-ID: <>

Brian Selzer wrote:

> "David BL" <> wrote in message
>> On Jul 3, 12:58 pm, "Brian Selzer" <> wrote:
>>> "David BL" <> 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.

Received on Mon Jul 06 2009 - 10:17:13 CEST

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