Roger Hui wrote: > The exclusion of tautologies as "a bit meta" points > to the definition of "natural" as "what John is used to" ;-) >
Point taken. > It not surprising that [ and ] etc. occur often in forks, > because many functions are not symmetric wrt the > left and right arguments. I am less concerned about [ and ] selecting arguments than the fork being effectively monadic at one end: my exclusion of [ and ] was a crude way of weeding these out. A large number of examples seemed to come down to (f x) g (x h y) and I was interested in seeing "natural" examples that are really doubly dyadic. It is much harder (at least for me) to come up with these, while I can do it with ease for monadic forks. > To find examples of the required forks, look for functions > that are symmetric (commutative). Symmetric functions are a good clue: I see now that mp - mp~ finds the commutator of two matrices (if mp=.+/ .*), however they cannot be all the good dyads. Best wishes, John ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
