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s(n) map
Based on\(f^x(x)\)
Growth rate\(f_{\omega^\omega}(n)\)

s(n) map is a functional, which is a function which maps functions to functions. It was defined by Japanese googologist Fish in 2002[1] and used to define Fish number 3. The name of the map was taken from the Japanese word shazou, which means mapping.

DefinitionEdit

\begin{eqnarray*} s(1)f & = & f^x(x) \\ s(n)f & = & s(n-1)^xf(x) (\text{if } n>1) \end{eqnarray*}

AnalysisEdit

Let \(f(x) = x+1\), and the growth rate can be calculated as:

\begin{eqnarray*} f^2(x) & = & x+2 \\ f^3(x) & = & x+3 \\ s(1)f(x) & = & f^x(x) = x+x = 2x \\ s(1)^2f(x) & = & g^x(x) = 2^x x \approx 2^x\text{, where }g(x)=2x \\ s(1)^3f(x) & \approx & h^{x}(x) \approx 2 \uparrow ^2 x \text{, where } h(x)=2^x \\ s(2)f(x) & = & s(1)^{x}f(x) \approx 2\uparrow ^x x \approx A(x,x) = A(1,0,x) \approx f_{\omega}(x) \end{eqnarray*}

Here, \(A\) is Taro's multivariable Ackermann function, where the growth rate in FGH is: \begin{eqnarray*} A(..., a3, a2, a1, a0, n) \approx f_{... + \omega^3・a3 + \omega^2・a2 + \omega・a1 + a0}(n) \end{eqnarray*}

Let \(f(n) = A(X, b, n)\) (X is a vector in any length), and: \begin{eqnarray*} A(X, b+1, n) & = & A(X, b, A(X, b+1, n-1)) \\ & = & f(A(X , b+1, n-1)) \\ & = & f^2(A(X, b+1, n-2)) \\ & = & … = f^n(A(X, b+1, 0)) \\ & \approx & f^n(n) \end{eqnarray*}

Therefore, comparing the 3 functions,

  • \(s(1)f(x) = f^x(x)\)
  • \(f_{\alpha+1}(n) = f^n_\alpha(n)\)
  • \(A(X, b+1, n) = f^n(n)\) where \(f(n) = A(X, b, n)\)

they all have similar growth rate. \(s(1)\) map has the same effect of adding 1 to the ordinal in FGH and adding 1 to the second parameter from right in the Ackermann function. This results in:

\begin{eqnarray*} s(1)s(2)f(x) & \approx & A(1,1,x) \approx f_{\omega + 1}(x) \\ s(1)^2 s(2)f(x) & \approx & A(1,2,x) \approx f_{\omega + 2}(x) \\ s(1)^n s(2)f(x) & \approx & A(1,n,x) \approx f_{\omega + n}(x) \end{eqnarray*}

and by diagonizing \(s(1)\) again,

\begin{eqnarray*} s(2)^2 f(x) = s(1)^x s(2)f(x) \approx A(1,x,x) = A(2,0,x) \approx f_{\omega \times 2}(x) \end{eqnarray*}

Here, the calculation of \(s(2)^2f(3)\) goes as follows:

\begin{eqnarray*} s(2)^2f(3) &=& s(1)^3s(2) f(3) \\ &=& [s(1)^2 s(2)f]^3(3) \\ &=& [s(1)^2 s(2)f]^2[[s(1)s(2)f]^3(3)] \end{eqnarray*}

For this calculation, by changing \(s(2)^2 f\) to \(f_{\omega \times 2}\), \(s(1)^3 s(2)f\) to \(f_{\omega+3}\), \(s(1)^2s(2)f\) to \(f_{\omega+2}\), and \(s(1)s(2)f\) to \(f_{\omega+1}\), respectively, the following is obtained:

\begin{eqnarray*} f_{\omega \times 2}(3) &=& f_{\omega+3}(3) \\ &=& f_{\omega+2}^3(3) \\ &=& f_{\omega+2}^2(f_{\omega+1}^3(3)) \end{eqnarray*}

which shows exactly how FGH is calculated.

Calculation goes in the same way:

\begin{eqnarray*} s(2)^n f(x) & \approx & A(n,0,x) \approx f_{\omega \times n}(x) \\ s(3)f(x) & = & s(2)^{x}f(x) \approx A(x,0,x) = A(1,0,0,x) \approx f_{\omega^2}(x) \\ s(3)^2 f(x) & \approx & A(2,0,0,x) \approx f_{\omega^2 \times 2}(x) \\ s(3)^n f(x) & \approx & A(n,0,0,x) \approx f_{\omega^2 \times n}(x) \\ s(4)f(x) & = & s(3)^{x}f(x) \approx A(x,0,0,x) = A(1,0,0,0,x) \approx f_{\omega^3}(x) \\ s(1)^4 s(2)^3 s(3)^2s(4)f(x) & \approx & A(1,2,3,4,x) \approx f_{\omega^3+\omega^2 \times 2+\omega \times 3 + 4}(x) \\ s(5)f(x) & \approx & f_{\omega^4}(x) \\ s(6)f(x) & \approx & f_{\omega^5}(x) \\ s(n)f(x) & \approx & f_{\omega^{n-1}}(x) \\ s(x)f(x) & \approx & f_{\omega^\omega}(x) \end{eqnarray*}

Therefore, by applying \(s(x)\) map, which diagonizes \(s(n)\) map, to the function \(f(x)=x+1\), the growth rate is \(f_{\omega^\omega}(x)\), similar to array notation and Taro's multivariable Ackermann function.

Sources Edit

  1. Fish, Googology in Japan - exploring large numbers (2013)

See alsoEdit

Googology in Asia

Fish numbers: Fish number 1 · Fish number 2 · Fish number 3 · Fish number 4 · Fish number 5 · Fish number 6 · Fish number 7
Mapping functions: S map · SS map · S(n) map · M(n) map · M(m,n) map
By Aeton: Okojo numbers · N-growing hierarchy
By BashicuHyudora: Pair sequence number · Bashicu matrix system
Indian counting system: Lakh · Crore
Chinese and Japanese counting system: Wan · Yi · Zhao · Jing · Gai · Zi · Rang · Gou · Jian · Zheng · Zai · Ji · Gougasha · Asougi · Nayuta · Fukashigi · Muryoutaisuu
Buddhist text: Tallakshana · Dvajagravati · Mahakathana · Asankhyeya · Dvajagranisamani · Vahanaprajnapti · Inga · Kuruta · Sarvanikshepa · Agrasara · Uttaraparamanurajahpravesa · Avatamsaka Sutra
Other: Taro's multivariable Ackermann function · Sushi Kokuuhen

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