
Overview


Tetration by Escape 
Tetration by Period 
My name is Daniel Geisler , welcome to my web site dedicated to promoting research into the question of what lies beyond exponentiation. Tetration is defined as iterated exponentiation but while exponentiation is essential to a large body of mathematics, little is known about tetration due to its chaotic properties. The standard notation for tetration is \(^{1}a=a, ^{2}a=a^a, ^{3}a=a^{a^a},\) and so on. Mathematicians have been researching tetration since at least the time of Euler but it is only at the end of the twentieth century that the combination of advances in dynamical systems and access to powerful computers is making real progress possible.
The big question in tetration research is how can tetration be extended to complex numbers. How do you compute numbers like \(^{.5}2\), and \(^{\pi i}e\) ? This web site will show how to compute these and other problems. See the Tetration page for a one page overview of extending tetration to the complex numbers.
Tetration isn't tetration anymore
The social abstract concept of tetration as a producer of fantastically large numbers has eclipsed it's original mathematical usage. As a researcher and mathematical community organizer I am quite displeased at how hard it is to find useful information about tetration research on search engines. Some tetration history. I am the senior researcher in tetration with fifty years of research and work to build a community for researches. This site is now twenty years old and before that I was on sci.math.research for a decade discussing tetration.
Note: Google "tetration cisco" to ignore Cisco Tetration and focus on tetration research.
Book of Numbers
Joshua Cohen wrote the highly rated Book of Numbers where the largest company in the world in is named Tetration.
Cisco Tetration
Here's some insight into Cisco Tetration  we can assume they think the idea of tetration is cool, but they have refused to reply to my friendly attempt at contact. So tetration now refers to two disjoint groups  mathematical researchers who live on meager means, but that history will likely remember with kindness. Then you have engineers making from $150 K to $200 K a year. Just note that the folks that allegedly thought of everything didn't think to connect or make the slightest alliance with the owner of Tetration.org. I will share more thoughts later.
So far I have been unable to reach either Joshua Cohen or Cisco Tetration management. :(
New at Tetration.org
Tetration.org is now twenty years old and in need of a complete rewrite which I am doing using MediaWiki with the Math extension. See http://iteratedfunctions.com/
Schroeder's Fourth Problem  OEIS A000311
The Schroeder tree graph of {{{1, 5}, 3}, {{2, 4}, 6}}
f[0] = 0;
s[1] = D[f[g[x]], {x, 1}] /. g[x] > 0;
s[n_] := D[f[g[x]], {x, n}] /. g[x] > 0 /. Derivative[1][f][0]*Derivative[n][g][x] > 0 /. Derivative[1][g][x] > l^(t  1)
dyn[1] = l^t; dyn[n_] := dyn[n] = Simplify[Sum[s[n], t] /. D[g[x], {x, m_}] :> dyn[m] /. l > Derivative[1][f][0]]
Hier[n_] := Block[{l = 1}, Sum[s[n], t] /. D[g[x], {x, m_}] :> dyn[m] /. t > 1 /. f > Exp]
Table[Hier[i], {i, 2, 15}]
Out[]= {1,4,26,236,2752,39208,660032,12818912,282137824,6939897856,188666182784,5617349020544,181790703209728,6353726042486272} 