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Home -> Community -> Usenet -> comp.databases.theory -> Re: SQL (was: Why using "Group By")
"Mikito Harakiri" <mikharakiri_at_ywho.com> wrote in message
news:1hvca.11$k63.50_at_news.oracle.com...
> "--CELKO--" <71062.1056_at_compuserve.com> wrote in message
> news:c0d87ec0.0303141635.612e1522_at_posting.google.com...
> > >>Do you have an example problem requiring recursion for which
> > transitive closure provides no solution? <<
> >
> > The Ackermann function, for one:
> >
> > A(0, m) = m+1
> > A(n+1, 0) = A(n, 1)
> > A(n+1, m+1) = A(n, A(n+1, m))
>
> Aha, I remember this one
>
>
http://www.google.com/groups?hl=en&lr=&ie=UTF-8&oe=UTF-8&selm=bdf69bdf.02010
> 70553.1dcb8788%40posting.google.com
>
> but could anybody provide more substantial reference?
Since A(n,m) = n + m + 1 | ( n in Integer, m in Integer, n >= 0, m >= 0 ), why do we need recursion for this function?
Don't get me wrong. I have no objection to recursion, per se. I am just curious where it is needed. Received on Fri Mar 14 2003 - 23:59:31 CST