:Talk:Sudan function

{{WikiProject banner shell|class=Stub|

}}

Please check wether the definition is good. My source isn't a very reliable one (random google search, namely [http://groups.google.com/group/soc.culture.romanian/tree/browse_frm/thread/7f684f8bd7f3edb1/]). I hope it's ok, however--it looks enough similarly to the Ackermann function to me to think it grows fast, as it should.

Is the table of values right?

I have an assignment for entry level Computer Science which is to implement the Sudan function recursively. I was trying to find some sample values to see if I had implemented it correctly, so I came to the wikipedia article. My program was not working- or so I thought. The table in the article is correct if you change the third condition's second argument to F(x, y) + y-----leaving out the plus 1. Can anyone more skilled speak to this?

137.54.8.99 (talk) 21:38, 15 March 2010 (UTC)

Follow up- I read it wrong. Article is right.

137.54.8.99 (talk) 21:43, 15 March 2010 (UTC)

What is exactly the Sudan function ?

The article does not say what the Sudan function exactly is, as it defines a sequence $(F_n)_{n\ge0}$ of functions.

Perhaps it should be more appropriate to write the function $F(n,x,y)$ whith three arguments. Pierre de Lyon 11:49, 19 May 2006 (UTC)

: Would that make the definition:

: $F(0, x, y) = x+y,\,$

: $F(n+1, x, 0) = x, \ n \ge 0\,$

: $F(n+1, x, y+1) = F(n, F(n+1, x, y), F(n+1, x, y) + y + 1), \ n\ge 0.\,$

: or shortened:

: $F(0, x, y) = x+y,\,$

: $F(n, x, 0) = x, \ n \ge 1\,$

: $F(n, x, y) = F(n-1, F(n, x, y-1), F(n, x, y-1) + y), \ n\ge 1.\,$

: ? - ℚuackor 20:02, 25 September 2007 (UTC)

:: This is exactly what I meant. By the way, I prefer the first definition which refers more to its inductive definition and makes a difference between the cases $0$ and $n+1$ . Pierre de Lyon 17:37, 30 October 2007 (UTC)

The function here doesn't match Sudan's paper

I checked both the 1979 article and the 1927 paper, and both of them describe Sudan's function as a function that uses transfinite recursion as follows:

: $\psi(a,b,0) = a+b$

: $\psi(a,b,n+1) = t_c(a,\lambda_m \psi(c,m,n),b)$

where

: $t_c(a,f(c),0) = a$

: $t_c(a,f(c),n+1) = f(t_c(a,f(c),n+1))$ .

I don't understand the functions in the paper well enough at the moment to interpret them. The source linked above attributes the function as given to MR 82k:03061 but I can't interpret this identifier. Arcorann (talk) 09:30, 1 May 2020 (UTC)