Re: SUPPORT FOR DECLARATIVE TRANSITION CONSTRAINTS
Date: Sun, 26 Sep 2010 10:41:58 -0300
Message-ID: <4c9f4d76$0$14798$9a566e8b_at_news.aliant.net>
Erwin wrote:
> On 25 sep, 22:41, Brian <br..._at_selzer-software.com> wrote:
>
>>The employee named paul c fills the position named toilet scrubber.
>>
>>Let's look at the information conveyed by this statement:
>>1. there is an employee named 'paul c.'
>>2. there is a position named 'toilet scrubber.'
>>3. the named employee fills the named position.
>>
>>Now, suppose that paul c's position changes from toilet scrubber to
>>floor sweeper.
>>
>>Assuming that no other proposition references an employee named paul c
>>or a position named toilet scrubber, doesn't the denial of
>>
>>(a) The employee named paul c fills the position named toilet
>>scrubber.
>>
>>also deny that there is an employee named paul c and that there is a
>>position named toilet scrubber?
>
>
> LOFL.
>
> Who again was it that should go back to school and take a course in
> logic ?
>
> EXISTS employee : employee(name) = 'paul c' && employee(position) =
> 'toilet scrubber' does indeed imply EXISTS employee : employee(name)
> = 'paul c' && EXISTS employee : employee(position) = 'toilet
> scrubber'. But note that the former and the latter are not
> equivalent, since the former conveys the extra information that the
> two properties apply to the very same person.
>
> NOT EXISTS employee : employee(name) = 'paul c' && employee(position)
> = 'toilet scrubber' ===
> FORALL employee : NOT(employee(name) = 'paul c' && employee(position)
> = 'toilet scrubber') ===
> FORALL employee : employee(name) <> 'paul c' OR employee(position)
> <> 'toilet scrubber')
>
> The denial of "(a) The employee named paul c fills the position named
> toilet scrubber." implies merely that if an employee is named paul c,
> then he is not a toilet scrubber, and also that if an employee is a
> toilet scrubber, then he is not named paul c.
>
> So the answer to your question "doesn't the denial of ... also
> imply ..." is, "No, doesn't.".
In addition to Erwin's fine work, I will direct Brian to POOD, as distasteful as it might sound in the context of toilet scrubbers. Received on Sun Sep 26 2010 - 15:41:58 CEST