Observations of 13 :'convertible explicit sentence' Produces a fork; never converts your sentence to a hook.
Given that the resulting tacit expression might be used any time in the future as a monad or as a dyad, the resulting fork uses [ or ] to exactly express your sentence. If 'explicit sentence' contains only y, the fork is written so that x cannot sneak in even when invoking the fork as a dyad. When 'explicit sentence' contains only x, the fork deliberately excludes y. However, J cannot* control that you might invoke your "dyadic sentence" as a monad. Since the monadic sames are equivalent the tacit expression effectively treats the lone y argument as if it were x. 13 :'explicit sentence containing only y' a fork with right same 13 :'explicit sentence containing only x' a fork with left same *footnote: J could inhibit the monadic case 13 : '*:x*4' NB. j fictitious example!!! [: : ([: *: 4 * [) However, I assume Ken & Roger were fully aware of these possibilities during language design and chose the more useful, less restrictive 13 : '*:x*4' NB. j 701. Notice [ [: *: 4 * [ You can mimic fictitious j: my_dyad=: [: : (13 : '*:x*4') NB. j 701 my_dyad [: :([: *: 4 * [) 8 my_dyad 'ignored' 1024 my_dyad 8 |domain error: my_dyad | my_dyad 8 ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
