It's not that they two frames have a common prefix, it's that one frame is a prefix of the other. And for that, as Roger said, an empty list is a prefix of any list.
In this case +"0 is equivalent to +, but the purpose of the example was to show nested " in action. For a verb like , the nesting would have an effect, but I thought that would be harder to make clear. Henry Rich > -----Original Message----- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] On Behalf Of Terrence Brannon > Sent: Friday, January 04, 2008 7:54 PM > To: J-general forum > Subject: [Jgeneral] 100 200 +"0"_ 0 (1 2 3) NB. there is no > common frame? > > I'm trying to trace the execution of > > 100 200 +"0"_ 0 (1 2 3) > > but it seems that the right and left frames do not have a prefix: > > Here is how I attempted to work out this expression: > > J Language Dyadic Verb Processing Worksheet > =========================================== > > Write out the entire expression: 100 200 +"0"_ 0 (1 2 3) > Write out the abbreviated verb rank: _ 0 > Expand the verb rank(*1): 0 _ 0 > > Rank Calculation: > ---------------- > left-noun-rank: 1 right-noun-rank: 1 > left-verb-rank: infinite right-verb-rank: 0 > lesser left rank, lr = 1 lesser right rank, rr = 0 > > The verb will be applied to 1-cells of the left operand > and 0-cells of the right operand. > > left-noun-shape: 2 right-noun-shape: 3 > > Frame Calculation per > http://www.jsoftware.com/jwiki/Essays/A_Fine_Line > -------------------------------------------------------------- > --------- > left-frame: lf = | 2 right-frame: rf = 3 | > > I.e - left frame is empty, right frame is 3 > > Result frame (longer of two): 3 > Common frame is prefix of the two: NO PREFIX... > > > > And that is where my attempt to solve this ends because I > thought that > the frames needed a common prefix if the shapes were not the same as > stated here - > > > http://www.jsoftware.com/help/jforc/loopless_code_i_verbs_have > _r.htm#_Toc141157994 > > > > > ---------------------------------------------------------------------- > For information about J forums see > http://www.jsoftware.com/forums.htm ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
