Re: XQuery question

From: Mikito Harakiri <mikharakiri_at_ywho.com>
Date: Thu, 8 May 2003 12:17:45 -0700
Message-ID: <H9yua.6$cw.52@news.oracle.com>

"Costin Cozianu" <c_cozianu_at_hotmail.com> wrote in message news:b9e86v$ie0us$1_at_ID-152540.news.dfncis.de...
> Incidentally this is the same with the infinte union of all powers of R
> R1= R union R^2 union R^3 union ....

If you have adjacency matrix A representing a DAG, then

TCA = I + A + A*A + A*A*A + ... where TCA is an adjacency matrix for transitive closure. Interestingly,

I + A + A*A + A*A*A + ... = (I - A)^(-1)

More interesting

exp(A) = I + A + A*A/2 + A*A*A/6 + ...

could be interpreted as transitive closure as well. Question:

what is transitive closure, exp(A), or (I - A)^(-1) ? Received on Thu May 08 2003 - 14:17:45 CDT