Arithmetic in the height-parameter (sums, series)
#1
Hi -

using the notation \( x_1 = \exp_b^{^{oh_1}}(x_0) \) and \( x_2 = \exp_b^{^{oh_2}}(x_1) \) we do arithmetic in the height (or "iteration") parameter like \( x_2 = \exp_b^{^{oh_1+h_2}}(x_0) \)

What about infinite series instead of a sum?
If we have a sufficient method for continuous tetration, then, for instance we should get
\( x_2 = \exp_b^{^{o1/2+1/4+1/8+...}}(x_0) = \exp_b^{^{o1}}(x_0) = b^{x_0} \)

For "nice" bases 1<= b <=ß (= exp(exp(-1)) ) we should get even more; I don't see any reason, why the series in the height-parameter should not be allowed to diverge.

So, with base b=sqrt(2) the following expression

\( y = \exp_b^{^{o1 + 2 + 4+ 8 +...}}(x_0) \)

seems to make sense to me because the partial evaluations converge to y=2 , for instance if we choose x_0 = 1.

On the other hand, the analytical continuation for the geometric series with constant quotient q \( g(q) = 1+q+q^2+ ... \) at q=2 gives

\( g(2) = 1/(1-2) = -1 \)

But -substitued this into the height-parameter- then we should also have

\( y = 2 = \exp_b^{^{o -1 }}(x_0) = \log_b(x_0) = \log_b(1) = 0 \)

where we see a contradiction.
So it seems to me that tetration can restrict the validity/range-of-usability of analytic continuation (if we do not have another explanation/notion/way-of-handling of such effects).

---

In a second view, this extends to other functions similarly. We have another inequality if a divergent series is used in the exponent of the power-function, for instance, to base e:

\( y = e^{^{-1 -2 -4 -8 -16 - \dots }} = \frac1{e^1}*\frac1{e^2}*\frac1{e^4} * \dots = 0 \neq e^1 \)


Just another plot of meditations... <phew>

Gottfried
Gottfried Helms, Kassel
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Messages In This Thread
Arithmetic in the height-parameter (sums, series) - by Gottfried - 02/04/2010, 05:08 PM

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