To be precise, f&.:g y [image: $\leftrightarrow$] gi f g y x f&.:g y [image: $\leftrightarrow$] gi (g x) f (g y)
and f&.g [image: $\leftrightarrow$] f&.:g"mg where mg is the monadic rank of g. I would change the Wiki page if it didn't seem heretical to correct Roger. Henry Rich On 1/6/2012 6:21 AM, Björn Helgason wrote: > 2012/1/6 Roger Hui<rogerhui.can...@gmail.com> > >> See http://www.jsoftware.com/jwiki/Essays/Under for examples of under. >> >> > I see gi is defined now > > f&.g y [image: $\leftrightarrow$] gi f g y > x f&.g y [image: $\leftrightarrow$] gi (g x) f (g y) > where gi is the inverse of g . "Under" elucidates the important but often > mysterious concept of duality in mathematics. > > Sometime long time ago I remember speculating what this gi was. > > Either it was not defined in the text or I failed to find it. > ---------------------------------------------------------------------- > For information about J forums see http://www.jsoftware.com/forums.htm > ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
