If A is nonnegative (<@I.@:*)A +-++---+-+ |2||0 3|2| +-++---+-+
Otherwise (0<@I.@:<])A +-++---+-+ |2||0 3|2| +-++---+-+ R.E. Boss > -----Oorspronkelijk bericht----- > Van: programming-boun...@forums.jsoftware.com > [mailto:programming-boun...@forums.jsoftware.com] Namens Linda Alvord > Verzonden: zondag 11 november 2012 11:17 > Aan: programm...@jsoftware.com > Onderwerp: Re: [Jprogramming] Arc consistency in J > > Mike, I think this will work as an alternative to adj > > A > 0 0 1 0 > 0 0 0 0 > 2 0 0 1 > 0 0 2 0 > adj > <@#&0 1 2 3@(0&<) > adj A > --TT---T-┐ > │2││0 3│2│ > L-++---+-- > h > 0 1 2 3 <@#~ 0 < ] > h A > --TT---T-┐ > │2││0 3│2│ > L-++---+-- > > Can anyone remove the final @ from h ? > > Linda > > > -----Original Message----- > From: programming-boun...@forums.jsoftware.com > [mailto:programming-boun...@forums.jsoftware.com] On Behalf Of Raul Miller > Sent: Saturday, November 10, 2012 12:44 PM > To: programm...@jsoftware.com > Subject: Re: [Jprogramming] Arc consistency in J > > On Sat, Nov 10, 2012 at 12:16 PM, Michal D. <michal.dobrog...@gmail.com> > wrote: > > Here X is telling us to use the constraint c1 (presumably b/c C is not > > shown) between the variables 1 and 3 (0 based). Likewise, use the > > transpose going the other direction (3,1). > > Ouch, you are correct, I did not specify C. On retesting, though, it looks > like my results stay the same when I use: > > arccon=:3 :0 > 'D c1 X'=: y > 'n d'=: $D > adj =: ((<@#)&(i.n)) @ (0&<) > A =: adj X > C=: a: , c1 ; (|:c1) > ac =: > @ (1&{) @ (revise^:_) @ ((i.n)&;) > ac D > ) > > For longer scripts like this, I really need to get into the habit of > restarting J for every test. So that probably means I should be using jhs. > > > Given the structure of X, only variables 1 and 3 can possibly change. > > So if they are all changing something is definitely wrong. > > This line of thinking does not make sense to me. I thought that the > requirement was that a 1 in D exists only when there is a valid relationship > along a relevant arc. If a 1 in D can also exist in the absence of any > relevant arc, I am back to needing a description of the algorithm. > > > Unfortunately I've run out of time to read the rest of your response > > but hopefully I can get through it soon. I've also wanted to write a > > simpler version of the algorithm where the right argument of ac is > > only D and it runs through all the arcs in the problem instead of > > trying to be smart about which ones could have changed. > > Yes... I am currently suspicious of the "AC-3 algorithm". > > In the case of symmetric consistency, I think that it's unnecessary > complexity, because the system converges on the initial iteration. > > In the case of asymmetric consistency, I think that the work involved in > maintaining the data structures needed for correctness will almost always > exceed the work saved. > > But I could be wrong. I am not sure yet if I understand the underlying > algorithm! > > -- > Raul > ---------------------------------------------------------------------- > For information about J forums see http://www.jsoftware.com/forums.htm > ---------------------------------------------------------------------- > For information about J forums see http://www.jsoftware.com/forums.htm ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
