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| <math>\int_0^{\infty}\left(\omega+\beta_i\right)^{\rho}\left[f\left(\omega+\beta_i\right)b^M\right]^{\rho + 1}e^{-\omega}d\omega = b^{M\rho+M}\int_0^{\infty}\sum_{k=0}^{\rho}\left(\right)\omega^k\beta_i^{\rho-k}\left[f\left(\omega+\beta_i\right)\right]^{\rho + 1}e^{-\omega}d\omega = b^{M\rho+M}\sum_{k=0}^{\rho}\left(\right)\beta_i^{\rho-k}\int_0^{\infty}\omega^k\left[f\left(\omega+\beta_i\right)\right]^{\rho + 1}e^{-\omega}d\omega</math> | | <math>\int_0^{\infty}\left(\omega+\beta_i\right)^{\rho}\left[f\left(\omega+\beta_i\right)b^M\right]^{\rho + 1}e^{-\omega}d\omega = b^{M\rho+M}\int_0^{\infty}\sum_{k=0}^{\rho}\left(\right)\omega^k\beta_i^{\rho-k}\left[f\left(\omega+\beta_i\right)\right]^{\rho + 1}e^{-\omega}d\omega = b^{M\rho+M}\sum_{k=0}^{\rho}\left(\right)\beta_i^{\rho-k}\int_0^{\infty}\omega^k\left[f\left(\omega+\beta_i\right)\right]^{\rho + 1}e^{-\omega}d\omega</math> |
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| The expression <math>f(\omega+\beta_i)</math> will again be some kind of <math>M</math>-th degree polynomial. But because the polynomial is zero for <math>\omega = 0</math> we know that the last coefficient is also equal to zero. | | :The expression <math>f(\omega+\beta_i)</math> will again be some kind of <math>M</math>-th degree polynomial. But because the polynomial is zero for <math>\omega = 0</math> we know that the last coefficient is also equal to zero. |
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| <math>b^{M\rho+M}\sum_{k=0}^{\rho}\left(\right)\beta_i^{\rho-k}\int_0^{\infty}\omega^k\left[f\left(\omega+\beta_i\right)\right]^{\rho + 1}e^{-\omega}d\omega = b^{M\rho+M}\sum_{k=0}^{\rho}\left(\right)\beta_i^{\rho-k}\int_0^{\infty}\left[b(\omega+\beta_i)^M + \text{ . . . }+b_M\right]^{\rho + 1}\omega^k e^{-\omega}d\omega = b^{M\rho+M}\sum_{k=0}^{\rho}\left(\right)\beta_i^{\rho-k}\int_0^{\infty}\left[l\omega^M + \text{ . . . }+\omega l_{M-1}\right]^{\rho + 1}\omega^k e^{-\omega}d\omega </math> | | <math>b^{M\rho+M}\sum_{k=0}^{\rho}\left(\right)\beta_i^{\rho-k}\int_0^{\infty}\omega^k\left[f\left(\omega+\beta_i\right)\right]^{\rho + 1}e^{-\omega}d\omega = b^{M\rho+M}\sum_{k=0}^{\rho}\left(\right)\beta_i^{\rho-k}\int_0^{\infty}\left[b(\omega+\beta_i)^M + \text{ . . . }+b_M\right]^{\rho + 1}\omega^k e^{-\omega}d\omega = b^{M\rho+M}\sum_{k=0}^{\rho}\left(\right)\beta_i^{\rho-k}\int_0^{\infty}\left[l\omega^M + \text{ . . . }+\omega l_{M-1}\right]^{\rho + 1}\omega^k e^{-\omega}d\omega </math> |
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| So, raised to the <math>\rho+1</math>-th power we get a polynomial again, but with the last <math>\rho</math> coefficients equal to zero. | | :So, raised to the <math>\rho+1</math>-th power we get a polynomial again, but with the last <math>\rho</math> coefficients equal to zero. |
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| <math>b^{M\rho+M}\sum_{k=0}^{\rho}\left(\right)\beta_i^{\rho-k}\int_0^{\infty}\left[l\omega^M + \text{ . . . }+\omega l_{M-1}\right]^{\rho + 1}\omega^k e^{-\omega}d\omega = b^{M\rho+M}\sum_{k=0}^{\rho}\left(\right)\beta_i^{\rho-k}\int_0^{\infty}\left(l'\omega^{M\rho+M} + \text{ . . . }+\omega^{\rho+1} l'_{M(\rho+1)-\rho -1}\right)\omega^k e^{-\omega}d\omega </math> | | <math>b^{M\rho+M}\sum_{k=0}^{\rho}\left(\right)\beta_i^{\rho-k}\int_0^{\infty}\left[l\omega^M + \text{ . . . }+\omega l_{M-1}\right]^{\rho + 1}\omega^k e^{-\omega}d\omega = b^{M\rho+M}\sum_{k=0}^{\rho}\left(\right)\beta_i^{\rho-k}\int_0^{\infty}\left(l'\omega^{M\rho+M} + \text{ . . . }+\omega^{\rho+1} l'_{M(\rho+1)-\rho -1}\right)\omega^k e^{-\omega}d\omega </math> |
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| We can "distribute" the integral into the sum | | :We can "distribute" the integral into the sum |
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| <math>b^{M\rho+M}\sum_{k=0}^{\rho}\left(\right)\beta_i^{\rho-k}\int_0^{\infty}\left(l'\omega^{M\rho+M} + \text{ . . . }+\omega^{\rho+1} l'_{M(\rho+1)-\rho -1}\right)\omega^k e^{-\omega}d\omega = b^{M\rho+M}\sum_{k=0}^{\rho}\left(\right)\beta_i^{\rho-k}\left(l'\int_0^{\infty}\omega^{M\rho+M}\omega^k e^{-\omega}d\omega + \text{ . . . }+l'_{M(\rho+1)-\rho -1}\int_0^{\infty}\omega^{\rho+1}\omega^k e^{-\omega}d\omega\right)</math> | | <math>b^{M\rho+M}\sum_{k=0}^{\rho}\left(\right)\beta_i^{\rho-k}\int_0^{\infty}\left(l'\omega^{M\rho+M} + \text{ . . . }+\omega^{\rho+1} l'_{M(\rho+1)-\rho -1}\right)\omega^k e^{-\omega}d\omega = b^{M\rho+M}\sum_{k=0}^{\rho}\left(\right)\beta_i^{\rho-k}\left(l'\int_0^{\infty}\omega^{M\rho+M}\omega^k e^{-\omega}d\omega + \text{ . . . }+l'_{M(\rho+1)-\rho -1}\int_0^{\infty}\omega^{\rho+1}\omega^k e^{-\omega}d\omega\right)</math> |
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| As above we can now use the fact that <math>\int_0^{\infty}\omega^{\rho}e^{-\omega}d\omega = \rho!</math> to get rid of the integrals; the expression becomes | | :As above we can now use the fact that <math>\int_0^{\infty}\omega^{\rho}e^{-\omega}d\omega = \rho!</math> to get rid of the integrals; the expression becomes |
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| <math>b^{M\rho+M}\sum_{k=0}^{\rho}\left(\right)\beta_i^{\rho-k}\left(l'\left(M\rho+M+k\right)! + \text{ . . . }+l'_{M(\rho+1)-\rho -1}\left(\rho+1+k\right)!\right) = b^{M\rho+M}\left(\rho+1\right)!\sum_{k=0}^{\rho}\left(\right)\beta_i^{\rho-k}\left(l'\frac{\left(M\rho+M+k\right)!}{\left(\rho+1\right)!} + \text{ . . . }+l'_{M(\rho+1)-\rho -1}\frac{\left(\rho+1+k\right)!}{\left(\rho+1\right)!}\right) = \left(\rho+1\right)!\cdot G\left(\beta_i\right)</math> | | <math>b^{M\rho+M}\sum_{k=0}^{\rho}\left(\right)\beta_i^{\rho-k}\left(l'\left(M\rho+M+k\right)! + \text{ . . . }+l'_{M(\rho+1)-\rho -1}\left(\rho+1+k\right)!\right) = b^{M\rho+M}\left(\rho+1\right)!\sum_{k=0}^{\rho}\left(\right)\beta_i^{\rho-k}\left(l'\frac{\left(M\rho+M+k\right)!}{\left(\rho+1\right)!} + \text{ . . . }+l'_{M(\rho+1)-\rho -1}\frac{\left(\rho+1+k\right)!}{\left(\rho+1\right)!}\right) = \left(\rho+1\right)!\cdot G\left(\beta_i\right)</math> |
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| where <math>G(\beta_i)</math> is a polynomial in <math>\beta_i</math> with integer coefficients. | | :where <math>G(\beta_i)</math> is a polynomial in <math>\beta_i</math> with integer coefficients. |
| </ref> | | </ref> |
| which tells us that the integral is equal to | | which tells us that the integral is equal to |
Revision as of 20:32, 24 January 2022
Pi is transcendental is a famous claim regarding the nature of the number .
It was first proven by Ferdinand von Lindemann in 1882, buildung on methods developed by Charles Hermite, who was able to prove that the number is transcendental roughly 10 years earlier in 1873.
With the help of Karl Weierstrass their findings could be generalized to the Lindemann-Weierstrass theorem in 1885.
Proof
The proof shown here is not the original proof by Lindemann but a later proof by David Hilbert which is a bit more accessible.
Suppose is algebraic.
Set
where is the imaginary unit .
Then is also algebraic, so it is the root of an
-th degree polynomial with integer coefficients.
Let be the other roots of this polynomial.
Since (Euler's identity) we have
for some .
These are also algebraic, since they are the sums of other algebraic numbers (the ).
Disregarding the that are equal to , we end up with
for some positive integer (since ).
Because the are algebraic,
they are the roots of a polynomial
with integer coefficients ,
and because no is equal to zero also.
First Part
First we will multiply our equation with the integral ,
where is some positive integer.
We will write as a shorthand.
This allows us to split the sum into two Parts:
where is a line integral along the line segment from to in the complex plane,
and is also a line integral obtained by integrating over the line from to parallel to the
real axis in the complex plane.
[1]
Second Part
The reason to do this is that, surprisingly, this turns most of the equation into integers.
First, one can show that is an integer
that is divisible by by expanding
to an integer polynomial and then using the fact that for positive integers .
[2]
More specifically, if divided by , one get's the remainder .
[3]
Third Part
Something slightly weaker can be shown for the terms .
Using the substitution we can set the bounds of integration to and ,
[4]
and then perform some similar algebraic manipulations so that we can use again,
[5]
which tells us that the integral is equal to
,
where is a polynomial in with integer coefficients.
Fourth Part
...
References
- ↑
If is a real number these integrals are just normal Riemann integrals over the real numbers, and it's easy to see that it's valid to split them up in this way.
So let be a complex number with imaginary part .
As above, is the integral along the line segment from to ,
along the line segment parallel to the real axis from to a number with real part ,
along the line segment parallel to the imaginary axis from to the real number ,
and along the real axis from to .
So is an integral along a closed path in the complex plane,
which is not self-intersecting if we choose large enough ().
Since the function which is being integrated is analytical on the whole complex plane this integral evaluates to zero according to the Cauchy integral theorem.
Note that if we let the lenght of the line segment from to stays the same
while the function tends towards zero on that line segment.
Using the estimation lemma for contour integrals it follows that
.
- ↑
-
where the are integers; if is a polynomial with integer coefficients so is .
The fractions are also integers because .
- ↑
Note that in the parentheses above every term is divisible by except the last one .
Hence, modulo we have the congruence ,
and since
.
- ↑
- ↑
We can expand the first factor using the binomial theorem
- The expression will again be some kind of -th degree polynomial. But because the polynomial is zero for we know that the last coefficient is also equal to zero.
- So, raised to the -th power we get a polynomial again, but with the last coefficients equal to zero.
- We can "distribute" the integral into the sum
- As above we can now use the fact that to get rid of the integrals; the expression becomes
- where is a polynomial in with integer coefficients.