Hello Raul, thanks for the explanation. I'm still trying to understand it, but I thini I got it.
Sorry my mistake about missing parenthesis. So, I'm missing the rule to understand this passage: ((2x&*) &1) 3 <---> ((2x&*)^:3) 1 But maybe this subject is too much advance for my J actual knowledge. thanks, Fausto 2015-02-19 14:48 GMT+01:00 Raul Miller <[email protected]>: > Please be careful here: > > 3 ((2x&*) &1) 3 > > is equivalent to each of these: > ((2x&*) &1) ((2x&*) &1) ((2x&*) &1) 3 > (((3(2x&*)1) (2x&*)1) (2x&*)1) > ((((2x&*)(2x&*)(2x&*)1) (2x&*)1) (2x&*)1) > ((8 (2x&*)1) (2x&*)1) > (((2x&*)(2x&*)(2x&*)(2x&*)(2x&*)(2x&*)(2x&*)(2x&*)1) (2x&*)1) > (256 (2x&*)1) > > and I'm not going to carry out the final step, which involves 256 > copies of the verb 2x&* > > Hopefully you can see why each of these expressions is equivalent. But > if something doesn't make sense, it's probably worth talking through > the issue (or at least showing a more gradual sequence of equivalences > for that step). > > On the other hand, > ((2x&*) &1^:3 3 > > is not a valid expression because of the unbalanced parenthesis. > > If you got rid of one of those left parenthesis, you'd get > (2x&*) &1^:3 3 > which is equivalent to > (2x&*) &1^:(3 3) > but that is a verb which you probably did not intend. > > If you instead insert a right parenthesis between the pair of threes, > you would get > ((2x&*) &1^:3) 3 > > which indeed is equivalent to your first expression. > > But note that you are not repeating three times 2x&* but instead are > repeating three times ((2x&*)1) in much the same manner as the > original expression. > > Thanks, > > -- > Raul > > > On Thu, Feb 19, 2015 at 8:11 AM, Fausto Saporito > <[email protected]> wrote: >> Hello Jose, >> >> I understand you are applying this identity : x u&n y <--> u&n^:x y >> >> But I cannot see the correct mapping in your expressions. >> I suppose this is an hook, so >> >> (u v) y --> y u v y >> >> 3 ((2x&*) &1) 3 >> >> ((2x&*) &1^:3 3 >> >> means repeat three times 2*1, i.e. 2*1*2*1*2*1 = 8 >> >> correct ? >> >> thanks, >> Fausto >> >> >> 2015-02-19 1:19 GMT+01:00 Henry Rich <[email protected]>: >>> If you're going to use dissect, get 3.6.42 (released today). Previous >>> versions had a confusing title for the verbs. >>> >>> Even with the picture it's amazing what this little phrase does. Two nested >>> powers, with the result of one power feeding back into the exponent of the >>> next iteration of the same verb. >>> >>> Henry Rich >>> >>> >>> On 2/18/2015 7:12 PM, Jose Mario Quintana wrote: >>>> >>>> ((2x&*) &1) 3 >>>> 8 >>>> ((2x&*)^:3) 1 >>>> 8 >>>> ((3x&*) &1) 2 >>>> 9 >>>> ((3x&*)^:2) 1 >>>> 9 >>>> >>>> >>>> Does dissect >>>> >>>> >>>> http://www.jsoftware.com/jwiki/action/show/Vocabulary/Dissect?action=show&redirect=Addons%2Fdebug%2Fdissect >>>> >>>> help to follow the execution of the sentences? >>>> >>>> >>>> >>>> >>>> >> ---------------------------------------------------------------------- >> 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
