Re: New package dependency field format
On Thursday 04 September 2003 19:17, Josip Rodin wrote:
> On Thu, Sep 04, 2003 at 07:40:19PM +0100, Andrew Suffield wrote:
> > > > > > Depends: foo | ! bar
> > > > > >
> > > > > > That can be read as "If bar is installed, then foo must also be
> > > > > > installed".
> > >
> > > Which is what "If bar is installed, then foo must also be installed"
> > > meant if you apply it only to the part after the pipe, as the present
> > > parser does... I didn't realize that you meant the whole expression
> > > means that.
> > >
> > > I guess it shows something about my vgrep, but also about the
> > > readability of such a thing.
> >
> > It would make sense if you'd studied formal logic >:)
> >
> > Conventionally, this is "A implies B", or A -> B. One of the
> > fundamental equivalences is then A -> B === B | !A
>
> Actually I am supposed to know that, it came up many times in various
> programming and mathematics classes. I guess I just wasn't reading
> properly. Sorry.
A -> B, in formal logic, does not mean that B -> A
ben
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