Oh, I'm sorry, I've been working with & so much lately that I used its rank. It should simply be

   ([: f g)"g <=> f@g

Henry Rich


On 12/21/2012 7:05 PM, Linda Alvord wrote:
Henry, I can't make your suggestion work.
    a
0 1 0 1 0 4
    b
0 0 2 3 2 3
    i=: 13 :'(=x) #@# y'
    i
] #@#~ [: = [
    a i b
3 2 1
    NB.  ([: f g)"({. g b. 0) <=> f@g
    k=: ] (([: # #)"({.# b. 0))~ [: = [
    k
] ([: # #)"_~ [: = [
    a k b
3

What am I missing?

Linda

-----Original Message-----
From: [email protected] 
[mailto:[email protected]] On Behalf Of Henry Rich
Sent: Friday, December 21, 2012 1:52 PM
To: [email protected]
Subject: Re: [Jprogramming] A Tree Question

Writing J without @@: is like writing English without the letter 'e'.  I don't 
know what it shows, and it sounds funny, but look! I did it.

     ([: f g) <=> f@:g
     ([: f g)"({. g b. 0) <=> f@g

Henry Rich

On 12/21/2012 1:30 PM, Linda Alvord wrote:
So how can you write an equivalent explicit expression that will have the same 
result of g without  @ or @: ?

-----Original Message-----
From: [email protected]
[mailto:[email protected]] On Behalf Of bob
therriault
Sent: Friday, December 21, 2012 1:02 PM
To: [email protected]
Subject: Re: [Jprogramming] A Tree Question

    Hi LInda,

Since forks result in verbs of infinite rank (unless changed by the
rank conjunction), #@# is not actually equivalent to ([:##), although
#@:# is. Watch what happens when I swap @: for @

   g=: 13 :'(=x) #@# y'
     a=:0 0 1 0 1 5
     b=:0 1 1 3 2 3
     a g b
3 2 1
     g1=:13 :'(=x) #@:# y'
     a g1 b
3

Cheers, bob

On 2012-12-21, at 9:51 AM, Linda Alvord wrote:

Why do the trees of  g  and  h appear to agree, but their results are
not the same?



     ]a=:?>:i.6

0 0 1 0 1 5

    ]b=:?>:i.6

0 1 1 3 2 3

    f=: 13 :'x#/.y'

    f

#/.

    a f b

3 2 1

    g=: 13 :'(=x) #@# y'

    g

] #@#~ [: = [

    a g b

3 2 1

    NB. x u@v y ↔ u x v y

    h=: 13 :'(=x) ([:##) y']

    h

(] ([: # #)~ [: = [) ]

    a h b

3

    5!:4 <'g'

   ┌─ ]
   │           ┌─ #
   ├─ ~ ─── @ ─┴─ #
──┤
   │     ┌─ [:
   └─────┼─ =
         └─ [

    5!:4 <'h'

       ┌─ ]
       │          ┌─ [:
       ├─ ~ ──────┼─ #
   ┌───┤          └─ #
   │   │     ┌─ [:
──┤   └─────┼─ =
   │         └─ [
   └─ ]

    g

] #@#~ [: = [

    h

(] ([: # #)~ [: = [) ]



Backtracking  i  and  j  are OK.



   i=: 13 :'x #@# y'

    i

#@#

    a i b

7

    j=: 13 :'#x#y'

    j

[: # #

    a j b

7

    5!:4 <'i'

       ┌─ #
── @ ─┴─ #

    5!:4 <'j'

   ┌─ [:
──┼─ #
   └─ #



I have tried to include rank of the verbs but I haven’t found the
right combination if that is what is necessary.



Linda

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