Shlomi Fish
Fri, 26 Oct 2001 00:10:05 -0700
On Thu, 25 Oct 2001, Adir Abraham wrote:
> Shlomi.. A joke is a joke only if it shouldn't be explained, and naturally
> is laughed (and understandable). If one (or more) does not laugh from a
> joke, either the joke is: 1) Not funny. 2) Not told to the right group (I
> wouldn't make jokes about computers infront of people who know history,
> for instance). 3) You are the only one who laughed from it and thought
> that it was funny, but it is not.
>
> In general.. if you are really seeking for "help" in "who will laugh from
> my joke", the joke is not a joke, or has one of the 3 reasons I told
> you (about why one wouldn't laugh from your joke). One of the best
> symptoms for a very bad joke is actually giving a very long explanation, a
> thing that Nadav tried to do (and I really don't know just like him why
> you actually picked him.)
>
> I guess that your say is good only as a signature :)
>
Well, insults taken aside, I still think some people (albeit a selected
few) will laugh from this joke.
Regards,
Shlomi Fish
> On Thu, 25 Oct 2001, Nadav Har'El wrote:
>
> > On Tue, Oct 23, 2001, Shlomi Fish wrote about "[Haifux] My New Signature
>re-factored.":
> > >
> > > Nadav, please tell me that at least you understood the joke. One righteous
> > > man in Sedom?
> >
> > Shlomi, I'm not sure why you decided to test me in public, or whether this is
> > a test of my Mathematical abilities or of my sense of humor... (I have masters
> > degree in the former, and a failure degree in the latter), or why this test
> > was aimed at me, of all people.
> >
> > But I'll bite...
> >
> > > If:
> > > 1. A is A
> > > 2. A is not not-A
> > > does it imply that
> > > 1. B is B
> > > 2. B is not not-B
> >
> > Why is this a "joke"? Is it supposed to be funny? How is it funny?
> >
> > Or is it some sort of deep logic thing? I read your forwarded post too, but
> > it didn't help me understand what you're talking about. Here is what I can
> > say about this issue:
> >
> > If a statement (call it S) is true for some "A", it isn't necessarily true for
> > another "B". Not unless you have another statement saying that the original
> > statement S is true for any object in the class Z, *and* that both A and
> > B are members of Z.
> >
> > But since your wrote specific, not general, statements about A and B, (in
> > our case S(x)="(x is x) AND (x is not not-x)", and we looked at the two
> > statements S(A) and S(B)) it is conceivable that S(x) be right or wrong for
> > *all* objects x of any type. For the answer to your question to be positive,
> > we need S(x) to have the same truth-value (true or false) for any x of any
> > type because we have no idea what type A or B is...
> >
> > But then a question arises - is your statement (S) at all defined for *all*
> > objects? Before you answer, remember that a "set of all objects" cannot
> > even be defined (it's easy to prove by paradox - ask me if you're interested).
> > Also remember that your statement is given in some sort of language (English,
> > logic, etc.) and it is not at all clear how it is defined for objects B
> > that cannot be expressed in that laguage at all...
> >
> > Here are two ways to try to understand what you wrote by trying to define
> > how your statement S works on large classes of objects (first, all objects
> > expressible by English, and then all objects expressible by logics). Neither
> > sounds very funny to me, nor very insightful, so maybe I'm missing something??
> >
> > If you define "is" and "not" for other classes of abstract objects, you
> > can get different answers....
> >
> > ======== The "natural language" way to understand S ============
> > In this case, the "B is not not-B" in the statement S(B) simply
> > means
> > "B" and "not B" are different things.
> >
> > This seems true for all English phrases B you can think of, but on second
> > thought it might not be (an example follows). If it can be true to A, and
> > false for B, then your question "does it imply" deserves the answer of no.
> >
> > For example, for A="True" (as an English word), we have A=A and A != not-A
> > ("true" and "not true" are different concepts in English).
> >
> > However, consider B="in a million years", as in the sentence "When will
> > I finish this project? In a million years!". Now, B ("in a million years") and
> > "not B" ("not in a million years") can mean exactly the same thing in
> > many contexts. For casual English (as opposed to Geology research papers),
> > B = not-B.
> >
> > I know this sounds really silly, but so does (sorry), the original question...
> > Unless I missed something really important...
> >
> > ======== The "logic" way to understand S ============
> > Normally, when you formulate the axioms of logics, you should have the
> > following axiom:
> >
> > For each truth value X (either TRUE or FALSE), you have the following
> > 1. X=X
> > 2. X=not not X
> > (you can call these axioms, or part of the definitions of = and not).
> >
> > This then extends to any "form", or function, that has an arbitrary number
> > of variables and produces a single truth value:
> > f=f
> > f=not not f
> >
> > [f=g should be understood as "f(x1,...,xn)=g(x1,...xn) for any choice of
> > truth values x1..xn. Also, not f is a function defined as (not f)(x1..xn)
> > = not (f(x1...xn)).]
> >
> > Example functions like that are CNF (conjunctive normal form) expressions,
> > and their "not" can be expressed as a CNF again using De-Morgan's law, by
> > the way.
> >
> > So your statement S(X) ("X is X, X is not not X") is true for any CNF
> > expression, be it called A or B, and so your question "does it imply"
> > deserves a "yes" answer in the context of CNF expressions.
> >
> >
> > --
> > Nadav Har'El | Thursday, Oct 25 2001, 9 Heshvan 5762
> > [EMAIL PROTECTED] |-----------------------------------------
> > Phone: +972-53-245868, ICQ 13349191 |If Windows is the answer, you didn't
> > http://nadav.harel.org.il |understand the question.
> >
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> >
> >
> >
>
----------------------------------------------------------------------
Shlomi Fish [EMAIL PROTECTED]
Home Page: http://t2.technion.ac.il/~shlomif/
Home E-mail: [EMAIL PROTECTED]
If:
1. A is A
2. A is not not-A
does it imply that
1. B is B
2. B is not not-B
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