Re: Mixing OO and DB
Date: Sat, 16 Feb 2008 08:57:59 -0800 (PST)
Message-ID: <17402b67-e5f1-4455-ba27-fe540bb1a42c_at_e25g2000prg.googlegroups.com>
On Feb 16, 3:39 am, "Dmitry A. Kazakov" <mail..._at_dmitry-kazakov.de>
wrote:
> On Fri, 15 Feb 2008 17:49:38 -0800 (PST), Marshall wrote:
>
> > Mathematically, a circle value is a set of points, and an ellipse
> > value is a set of points.
>
> Geometry does not operate "values".
> It deals with plain circles and ellipses.
> In a computational system that models geometrical
> objects a circle value serves as a model of circle.
> > Mathematically, we can describe a set of points
> > with an equation, and the equation that describes ellipses reduces
> > to the equation that describes circles in certain cases. Do you want
> > to say that two different appearances of the same equation may be
> > different depending on what they were reduced from? That dog
> > won't hunt.
>
> It can also define a circle using its center and radius, or as a conic
> section, or via complex exponent, or by an uncountable number of other
> ways. All these definitions are said equivalent. It has nothing to do with
> being "same value".
> > I happen to think type systems are just about the most interesting
> > thing in computer science, but I don't make the mistake of thinking
> > that they are somehow fundamentally necessary, or worse, that
> > the state of the art of today's industrial languages (which is decades
> > behind the state of the art of today's academic languages) is
> > somehow the end of the road.
>
> Just a comment, mathematicians understood need in typed systems
> hundred years before us.
As I understand it, type theory arose from Russel's desire to patch up Frege's naive set theory after his discovery of what is now called Russel's paradox. However most set theories today are untyped; there turn out to be easier ways to deal with Russel's paradox than types.
Marshall Received on Sat Feb 16 2008 - 17:57:59 CET