That is a very special case in more than one way. See http://www.jsoftware.com/help/dictionary/samp21.htm for other examples.
----- Original Message ----- From: david alis <[EMAIL PROTECTED]> Date: Sunday, April 20, 2008 4:31 Subject: [Jgeneral] transitive closure question and directed graphs To: [email protected] > The Dictionary contains a discussion about transitive closure in the > entry for ^: > http://www.jsoftware.com/help/dictionary/d202n.htm > > Example 5 starts as follows: > x=: (#x)<. (#x),~x=: (i.20)+1+20 [EMAIL PROTECTED] 3 > (i.#x) ,: x > 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 > 1 4 5 5 7 6 9 9 10 12 11 14 14 15 16 18 18 18 20 20 20 > and includes the remark: > Interpretation: x specifies a directed graph with nodes numbered i.#x > and links from i to i{x . For example, the links are: 0 1 > , 1 4 , 2 5 > , 3 5 and so on. Then {&x^:a:0 or x{~^:a:0 computes all the nodes > reachable from node 0. > > My question is about x being a directed graph. > Do all directed graphs consist of as many links as there are nodes? > Or is this example in some sense a special case? ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
