I stand corrected. On Mon, Apr 5, 2010 at 12:26 AM, Oleg Kobchenko <[email protected]> wrote:
> Correction: e. is like "element of" in mathematics, > denoted by ∈. > > "Exists" in mathematics, denoted by upside-down E, > would be a predicate aggregate (Insert) with Or. > > exists=: (+./)@: NB. there exists yy e. y : 1 = u yy > > >&0 exists _1 0 2 > 1 > >&0 exists _1 0 _2 > 0 > > all=: (*./)@: NB. for all yy e. y : 1 = u yy > > >&0 all _1 0 2 > 0 > >&0 all 1 3 2 > 1 > > > > > > > From: Don Guinn <[email protected]> > > e. is like exists in mathematics. > > rtn=:'YES';'NO';'MAYBE' > rtn > +---+--+-----+ > |YES|NO|MAYBE| > +---+--+-----+ > rtn e. <'NO' > 0 1 0 > (<'NO') e. rtn > 1 > > Your expression > (first) asks if each atom of rtn exists in <'NO'. Which the > second atom of rtn does. The first and third do not. > > I think that what > you really want is the second expression which asks if > <'NO' > exists anywhere in rtn. > > Have you looked up e. in the dictionary? > Lots of information there. In J it > is not really necessary to do I/O > all over the place to see what's going on. > Don't try to do something > big at first. Avoid comparing J to other > languages. It can slow your > understanding of J down. Play a little. > > > > > ---------------------------------------------------------------------- > For information about J forums see http://www.jsoftware.com/forums.htm ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
