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From: uccjcm@ecsvax.UUCP (Jonathon C. McLendon IV)
Newsgroups: comp.lang.c
Subject: Re: what "cast" means
Message-ID: <3696@ecsvax.UUCP>
Date: Wed, 12-Aug-87 16:43:05 EDT
Article-I.D.: ecsvax.3696
Posted: Wed Aug 12 16:43:05 1987
Date-Received: Sat, 15-Aug-87 01:55:44 EDT
References: <263@auvax.UUCP> <1987Jul9.162103.1701@sq.uucp> <243@wrs.UUCP> <190@xyzzy.UUCP>
Organization: UNC Educational Computing Service
Lines: 47
Summary: Oops!!!

In article <190@xyzzy.UUCP>, throopw@xyzzy.UUCP (Wayne A. Throop) writes:
> > uccjcm@ecsvax.UUCP (Jonathon C. McLendon IV)
> >> okunewck@psuvax1.psu.edu (Philip E. OKunewick)
> 
> >>>> [not looking like Pascal is not a language deficiency]
> >>>does this mean that "looking like Pascal is a language deficiency!" :-)
> 
> Actually, Philip is correct and Jonathon is quite wrong.

Correct, I was wrong. I attribute this to a minor phase transformation
when materializing during deceleration to sub-light speed.

> 
> In particular, (not (implies (not A) B)) reduces to (and (not A) (not B)),
> while (implies A (not B)) reduces to (or (not A) B).
> 
> Reducing these claims, the first one becomes
>         (exists l (not (implies (not (pascalllike l) (deficient l)))))
> which becomes
>         (exists l (and (not (pascalllike l)) (not (deficient l))))

        Neither of these is reduced, therefore, their non-equivalence
        proves nothing.

There is a much simpler way to do this, and without all the parenthesis.

I. Assume A implies B, then not B implies not A follows directly.
   The contra-positive of this [Assume not B implies not A...] also
   follows directly.

Apply the contra-positive to the statement "Not looking like Pascal implies
not a language deficiency." One obtains "A language deficiency implies
looking like Pascal" which is not "Looking like Pascal implies a language
deficiency." These are the proper reduced statements, and they are not 
equivalent.
QED
        (Note that the "implies" above are one-way, that is, they are not
         "if and only if.")


Now, this is really not a proper subject for comp.lang.c, so I will have
no further responses. All flamage, slammage, damage to /dev/null please.
-- 
Signed:
            Jonathon C. McLendon IV    -> ecsvax!uccjcm (919) 962-3228
            My employer has no opinions that aren't my own...
               (Or is it the other way around?)