[net.ai] The Analog/Digital Distinction: Sol

goldfain@uiucuxe.CSO.UIUC.EDU (10/27/86)

Analog devices/processes are best viewed as having a continuous possible
range of values.  (An interval of the real line, for example.)

Digital devices/processes are best viewed as having an underlying granularity
of discrete possible values.  (Representable by a subset of the integers.)

			-----------------

This is a pretty good definition, whether you like it or not.

I am curious as to what kind of discussion you are hoping to get, when you
rule out the correct distinction at the outset ...

harnad@mind.UUCP (Stevan Harnad) (10/29/86)

Concerning the A/D distinction, goldfain@uiucuxe.CSO.UIUC.EDU replies:

>	Analog devices/processes are best viewed as having a continuous possible
>	range of values.  (An interval of the real line, for example.)
>	Digital devices/processes are best viewed as having an underlying
>	granularity of discrete possible values.
>	(Representable by a subset of the integers.)
>	This is a pretty good definition, whether you like it or not.
>	I am curious as to what kind of discussion you are hoping to get,
>	when you rule out the correct distinction at the outset ...

Nothing is ruled out. If you follow the ongoing discussion, you'll see
what I meant by continuity and discreteness being "nonstarters." There
seem to be some basic problems with what these mean in the real
physical world. Where do you find formal continuity in physical
devices? And if it's only "approximate" continuity, then how is the
"exact/approximate" distinction that some are proposing for A/D going
to work? I'm not ruling out that these problems may be resolvable, and
that continuous/discrete will emerge as a coherent criterion after
all. I'm just suggesting that there are prima facie reasons for
thinking that the distinction has not yet been formulated coherently
by anyone. And I'm predicting that the discussion will be surprising,
even to those who thought they had a good, crisp, rigorous idea of
what the A/D distinction was.


Stevan Harnad
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