Interval Index is just finding the index of an item in a sorted list. Not really all that novel (binary search, etc.) In 1987 I did not have it as a primitive and solved the problem with one application of the monad /: .
----- Original Message ----- From: Oleg Kobchenko <[EMAIL PROTECTED]> Date: Wednesday, April 2, 2008 16:40 Subject: Re: [Jgeneral] Transitive Closure and Line Wrap To: General forum <[email protected]> > Speaking of efficiency in > http://www.jsoftware.com/jwiki/Essays/Text_Formatting > the key is Interval Index, which is not > mentioned except in formula. Given its novelty, > it may be easily overlooked. > > It might be good also besides spelling it out > to provide a link to Dictionary inline and/or in > See Also. It not easy to get there from the > Wiki page. > > > --- Roger Hui <[EMAIL PROTECTED]> wrote: > > > The ^: dictionary page contains two examples (examples 5 and 6) > > of computing the transitive closure efficiently. > > > > http://www.jsoftware.com/help/dictionary/d202n.htm > > > > > > > > ----- Original Message ----- > > From: Roger Hui <[EMAIL PROTECTED]> > > Date: Wednesday, April 2, 2008 7:53 > > Subject: Re: [Jgeneral] Transitive Closure and Line Wrap > > To: General forum <[email protected]> > > > > > An explanation of closure usually begins with a description of > > > graphs and then proceeds to closure. From the J dictionary: > > > > > > http://www.jsoftware.com/help/dictionary/samp20.htm > > > (Directed Graphs) > > > http://www.jsoftware.com/help/dictionary/samp21.htm (Closure) > > > > > > One particular kind of graph provides a telling example: > > > the relation ship is "children of". The transitive closure > > > of this graph is "descendant of". "Transitive" means > > > if a R b and b R c, then a R c . ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
