Re: Using the RM for ADTs

From: Brian Selzer <>
Date: Sat, 4 Jul 2009 06:13:44 -0400
Message-ID: <tXF3m.1849$>

"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. Received on Sat Jul 04 2009 - 12:13:44 CEST

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