Re: Question about Date & Darwen <OR> operator

VC wrote:
> "Mikito Harakiri" <mikharakiri_nospaum_at_yahoo.com> wrote in message
> news:1125711068.995070.322110_at_g44g2000cwa.googlegroups.com...
> [...]
> > Well, the formal definition of <OR> and <AND> seems to be very
> > consistent with boolean logic. Take
> >
> > Relation A
> > x y
> > - -
> > 1 a
> > 2 b
> >
> > and
> >
> > Relation B
> > y z
> > - -
> > a #
> > b %
> >
> > Then, formally relation A is a proposition
> >
> > x=1 & y=a \/ x=2 & y=b
> >
> > while relation B is
> >
> > y=a & z=# \/ y=b & z=%
> >
> > The <OR> is just formal disjunction
> >
> > x=1 & y=a \/ x=2 & y=b \/ y=a & z=# \/ y=b & z=%
> >
> > that could be equivalently transformed into
> >
> > x=1 & y=a & z=# \/
> > x=1 & y=a & z=% \/
> > x=2 & y=b & z=# \/
> > x=2 & y=b & z=% \/
> > x=1 & y=a & z=# \/
> > x=2 & y=a & z=# \/
> > x=1 & y=b & z=% \/
> > x=2 & y=b & z=%
> >
>
> The above transformation ain't correct. In fact such transformation cannot
> be performed because x,y and z's domains are not specified.

Well, it's not that hard to fix it, right? If domain z is {#,$,%} then the first conjunct

x=1 & y=a

expands into

x=1 & y=a & z=# \/
x=1 & y=a & z=$ \/
x=1 & y=a & z=% \/

etc. Received on Tue Sep 06 2005 - 05:12:03 CEST