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JSH  
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(2 users)  More options Sep 6, 4:00 am
Newsgroups: alt.math.undergrad, alt.math.recreational, sci.math
From: JSH <jst...@gmail.com>
Date: Fri, 5 Sep 2008 13:00:52 -0700 (PDT)
Local: Sat, Sep 6 2008 4:00 am
Subject: Quadratic Diophantine Theorem
Quadratic Diophantine Theorem:

In the ring of integers, given the quadratic expression

c_1*x^2 + c_2*xy + c_3*y^2 = c_4*z^2 + c_5*zx + c_6*zy

where the c's are constants, for solutions to exist it must be true
that

((c_2 - 2c_1)^2 + 4c_1*(c_2 - c_1 - c_3))v^2 + (2(c_2 - 2c_1)*(c_6 -
c_5) + 4c_5*(c_2 - c_1 - c_3))v + (c_6 - c_5)^2 - 4c_4*(c_2 - c_1 -
c_3) = n^2 mod p

for some n, where p is any prime coprime to z for a given solution,
when

v = -(x+y)z^{-1} mod p.

For example with x^2 + y^2 = z^2, I have

c_1 = 1, c_2 = 0, c_3 = 1, c_4 = 1, c_5 = 0, and c_6 = 0

which gives

-4v^2 + 8 = n^2 mod p

for every prime coprime to z, for some n (remember ring is ring of
integers) when v = -(x+y)z^{-1} mod p.

Making the substitution for v gives

-4(-(x+y)z^{-1})^2 + 8 = n^2 mod p

so

-4(x+y)^2 + 8z^2 = n^2*z^2 mod p

and since x^2 + y^2 = z^2, I can substitute out z, to get

4(x-y)^2 = n^2*z^2 mod p

so the requirement is met, as of course, there are an infinity of
integer solutions to x^2 + y^2 = z^2.

And a square was required here because p can be any prime coprime to a
solution for z, so an infinite number of primes must work!

Notice that the result also applies to the general diophantine
quadratic in 2 variables by making c_1 = 0 and x=1.

The theorem is proven easily using what I call tautological spaces.

James Harris


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Dirk Van de moortel  
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(1 user)  More options Sep 6, 6:00 am
Newsgroups: alt.math.undergrad, alt.math.recreational, sci.math
From: "Dirk Van de moortel" <dirkvandemoor...@nospAm.hotmail.com>
Date: Sat, 6 Sep 2008 00:00:44 +0200
Local: Sat, Sep 6 2008 6:00 am
Subject: Re: Quadratic Diophantine Theorem
JSH <jst...@gmail.com> wrote in message

  7ce79450-0709-4634-b6b7-095b7a59e...@v13g2000pro.googlegroups.com

> Quadratic Diophantine Theorem:

[snip]

> The theorem is proven easily using what I call tautological spaces.

The famous spaces in which whatever pops into
James Harris' mind is correct by proxy.

Dirk Vdm


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JSH  
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(2 users)  More options Sep 6, 8:01 am
Newsgroups: alt.math.undergrad, alt.math.recreational, sci.math
From: JSH <jst...@gmail.com>
Date: Fri, 5 Sep 2008 17:01:44 -0700 (PDT)
Local: Sat, Sep 6 2008 8:01 am
Subject: Re: Quadratic Diophantine Theorem
On Sep 5, 3:00 pm, "Dirk Van de moortel"

<dirkvandemoor...@nospAm.hotmail.com> wrote:
> JSH <jst...@gmail.com> wrote in message

>   7ce79450-0709-4634-b6b7-095b7a59e...@v13g2000pro.googlegroups.com

> > Quadratic Diophantine Theorem:

> [snip]

> > The theorem is proven easily using what I call tautological spaces.

> The famous spaces in which whatever pops into
> James Harris' mind is correct by proxy.

> Dirk Vdm

Nope.  The theorem is absolutely correct.

The only question is, how useful is it?

James Harris


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Rotwang  
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(1 user)  More options Sep 6, 12:21 pm
Newsgroups: alt.math.undergrad, alt.math.recreational, sci.math
From: Rotwang <sg...@hotmail.co.uk>
Date: Fri, 5 Sep 2008 21:21:58 -0700 (PDT)
Local: Sat, Sep 6 2008 12:21 pm
Subject: Re: Quadratic Diophantine Theorem
On 5 Sep, 21:00, JSH <jst...@gmail.com> wrote:

I don't see that you need to use "tautological spaces" to prove this -
it's just a matter of school level arithmetic to verify that the left
hand side of (1) is given by

z^{-2} ((c_2 - 2*c_1)x - (c_2 - 2*c_3)y - (c_6 - c_5)z)^2

which is clearly a square. But I don't see what the point of this is,
and furthermore it is easy to generate a load of other such
expressions; just start with a Diophantine equation, take the square
of some arbitrary expression involving the variables and constants
occurring in the expression and then make some substitutions. Can you
present some use of your theorem, i.e. can you use it to prove
something which isn't easy to prove by other means?


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Tim Smith  
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 More options Sep 6, 1:04 pm
Newsgroups: alt.math.undergrad, alt.math.recreational, sci.math
From: Tim Smith <reply_in_gr...@mouse-potato.com>
Date: Fri, 05 Sep 2008 22:04:09 -0700
Local: Sat, Sep 6 2008 1:04 pm
Subject: Re: Quadratic Diophantine Theorem
In article <t_hwk.629411$7f3.176...@newsfe23.ams2>,
 "Dirk Van de moortel" <dirkvandemoor...@nospAm.hotmail.com> wrote:

> JSH <jst...@gmail.com> wrote in message
>   7ce79450-0709-4634-b6b7-095b7a59e...@v13g2000pro.googlegroups.com
> > Quadratic Diophantine Theorem:

> [snip]

> > The theorem is proven easily using what I call tautological spaces.

> The famous spaces in which whatever pops into
> James Harris' mind is correct by proxy.

Do you happen to have a counterexample to his alleged theorem, or some
other way to show that it is not correct?

--
--Tim Smith


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Rotwang  
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(1 user)  More options Sep 6, 1:12 pm
Newsgroups: alt.math.undergrad, alt.math.recreational, sci.math
From: Rotwang <sg...@hotmail.co.uk>
Date: Fri, 5 Sep 2008 22:12:34 -0700 (PDT)
Local: Sat, Sep 6 2008 1:12 pm
Subject: Re: Quadratic Diophantine Theorem
On 6 Sep, 06:04, Tim Smith <reply_in_gr...@mouse-potato.com> wrote:

No, he doesn't; on this occasion James' theorem is true (see my
earlier post where I point out how to prove it).

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Dirk Van de moortel  
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(1 user)  More options Sep 6, 4:37 pm
Newsgroups: alt.math.undergrad, alt.math.recreational, sci.math
From: "Dirk Van de moortel" <dirkvandemoor...@nospAm.hotmail.com>
Date: Sat, 6 Sep 2008 10:37:02 +0200
Local: Sat, Sep 6 2008 4:37 pm
Subject: Re: Quadratic Diophantine Theorem
Tim Smith <reply_in_gr...@mouse-potato.com> wrote in message

  reply_in_group-A24F6C.22040805092...@news.supernews.com

I never even *look* at anything between his opening and closing
line anymore.
Not after this:
  http://users.telenet.be/vdmoortel/dirk/Physics/Fumbles/ArmyMath.html

Dirk Vdm


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Joshua Cranmer  
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(1 user)  More options Sep 6, 9:28 pm
Newsgroups: alt.math.undergrad, alt.math.recreational, sci.math
From: Joshua Cranmer <Pidgeo...@gmail.com>
Date: Sat, 06 Sep 2008 09:28:19 -0400
Local: Sat, Sep 6 2008 9:28 pm
Subject: Re: Quadratic Diophantine Theorem
Dirk Van de moortel wrote:

> I never even *look* at anything between his opening and closing
> line anymore.
> Not after this:
>  http://users.telenet.be/vdmoortel/dirk/Physics/Fumbles/ArmyMath.html

His non sequiturs are half the reason I haven't kill-filed him. The
mathematical content doesn't interest me too much--I've not studied
higher-level algebras, so the only thing I've really paid close
attention to is his TSP work.

In any case, that posting is quite enlightening, given conversations
with certain [insert favorite branch of the armed forces] officers.

Also, JSH being relatively empty from your list of... postings does seem
to reinforce what I've seen, i.e., he's relatively light compared to
other people. You should probably put Androcles on a separate page, BTW.


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Frederick Williams  
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(1 user)  More options Sep 6, 10:49 pm
Newsgroups: alt.math.undergrad, alt.math.recreational, sci.math
From: Frederick Williams <frederick.willia...@tesco.net>
Date: Sat, 06 Sep 2008 15:49:32 +0100
Local: Sat, Sep 6 2008 10:49 pm
Subject: Re: Quadratic Diophantine Theorem

JSH wrote:

> Nope.  The theorem is absolutely correct.

Show us the proof then!

> The only question is, how useful is it?

--
He is not here; but far away
  The noise of life begins again
  And ghastly thro' the drizzling rain
On the bald street breaks the blank day.

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Dirk Van de moortel  
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(1 user)  More options Sep 6, 10:54 pm
Newsgroups: alt.math.undergrad, alt.math.recreational, sci.math
From: "Dirk Van de moortel" <dirkvandemoor...@nospAm.hotmail.com>
Date: Sat, 6 Sep 2008 16:54:08 +0200
Local: Sat, Sep 6 2008 10:54 pm
Subject: Re: Quadratic Diophantine Theorem
Joshua Cranmer <Pidgeo...@gmail.com> wrote in message

  g9u0hj$g0...@aioe.org

heh... the page started with Androcles,  but it quickly turned
out he was not the only loon in town ;-)

Dirk Vdm


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JSH  
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(2 users)  More options Sep 6, 11:15 pm
Newsgroups: alt.math.undergrad, alt.math.recreational, sci.math
From: JSH <jst...@gmail.com>
Date: Sat, 6 Sep 2008 08:15:39 -0700 (PDT)
Local: Sat, Sep 6 2008 11:15 pm
Subject: Re: Quadratic Diophantine Theorem
On Sep 6, 7:49 am, Frederick Williams <frederick.willia...@tesco.net>
wrote:

> JSH wrote:

> > Nope.  The theorem is absolutely correct.

> Show us the proof then!

It is on my math blog.

James Harris


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