I do not think the dictionary is wrong but perhaps it is incomplete. As you pointed out, the tally is 1 and the neutral element intance provision does not apply; so, for example, in the sentence (*/0) or in general (u/A) where A is an atom the result is the atom (A) (even if u is undefined!). Where is this documented?
This "feature" seems to make sense at first glance; however, it has tripped me up at least once before. On Wed, Sep 10, 2014 at 11:42 AM, Jan-Pieter Jacobs < janpieter.jac...@gmail.com> wrote: > I think the manual page on insert ( > http://www.jsoftware.com/help/dictionary/d420.htm ) sufficiently > explains this behavior: > > "0 makes the function operate on scalars and, as per the Vocabulary on > Insert (/) : > > " If y has no items (that is, 0=#y), the result of u/y is the neutral > or identity element of the function u . A neutral of a function u is a > value e such that x u e ↔ x or e u x ↔ x, for every x in the domain > (or some significant sub-domain such as boolean) of u . This > definition of insertion over an argument having zero items extends > partitioning identities of the form u/y ↔ (u/k{.y) u (u/k}.y) to the > cases k e. 0,#y ." > > I do think there is something not right in the vocabulary (excuse the > blasphemy) with the requirement of 0=#y, since # equals 1 for scalars. > Using $$ instead would make it correct though. > Hope this helps > > Jan-Pieter > > 2014-09-10 17:24 GMT+02:00 Joe Bogner <joebog...@gmail.com>: > > On Wed, Sep 10, 2014 at 9:57 AM, Linda Alvord <lindaalv...@verizon.net> > > wrote: > > > >> > >> Here's the example that is puzzling me. > >> > >> *i.5 > >> 0 1 1 1 1 > >> */"0 i.5 > >> 0 1 2 3 4 > >> > >> > > It looks like /"0 yields the right side without evaluating the left side > > > > asdfasdf/"0 i.5 > > > > 0 1 2 3 4 > > > > > > This might be helpful in understanding: > > > http://jsoftware.2058.n7.nabble.com/Adverb-and-conjunction-parsing-rules-td2021.html#a2022 > > ... I don't totally get it myself so I can't explain it any further than > > sharing what I found. > > ---------------------------------------------------------------------- > > 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
