It appears to be due to the boolean list special code: c1 =: 3 : '3!:0 (2 | y) ] (2 | y) } y ,: (2 + 6 * y)'
c2 =: 3 : 0 a =: 2 | y b =: 2 + 6 * y c =: a } y ,: b 3!:0 a ) c1 T 4 c2 T 1 On Thu, Aug 7, 2014 at 9:24 AM, Raul Miller <[email protected]> wrote: > That was my original impression. > > But then I looked at the right hand side of the expression: > > Why is it labelled x,y,:z and why does the text mention the case > c}x,y,...,:z? > > It might be that this was originally a more ambitious project and that > Roger got interrupted before he finished it. > > Anyways, it is interesting to me that the wiki page is silent about this > explicitly documented issue. > > -- > Raul > > > > On Thu, Aug 7, 2014 at 8:53 AM, Henry Rich <[email protected]> wrote: > >> 'boolean' here means that 3!:0 returns 1; the values are restricted to >> {0,1}. Details at >> >> http://www.jsoftware.com/jwiki/Vocabulary/SpecialCombinations# >> Assignments_In_Place_.28AIP.29 >> >> >> Henry Rich >> >> >> On 8/7/2014 8:42 AM, Raul Miller wrote: >> >>> I think http://jsoftware.com/help/release/iamend.htm might be relevant. >>> >>> Note also that in this case I'm not sure if "boolean" really means >>> "non-negative integer". (If I understand properly: in George Boole's >>> arithmetic these were equivalent, and some of the details here suggest >>> that >>> that original meaning might be relevant here. It's a confusing topic >>> though >>> because it has become popular, depending on context, to assert that >>> "boolean" can only refer to the values 0 and 1 and also that "boolean" >>> cannot be used to refer to the values 0 and 1.) >>> >>> Thanks, >>> >>> ---------------------------------------------------------------------- >> 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
