If I interpret you correctly, please advice if I do not, you are
stating that the rank, domain and mapping of the generic verbs (u @ v)
and (u at v) are the same but you are not (directly) stating that they
are equivalent within a meaningful (without cheating) context, for
example, you are not (directly) stating that (u @ v @ w) and (u at v @
w), or (u @ v (@ w)) and (u at v (@ w)), or (u @ v (d.1)) and (u at v
(d.1)) are each pairwise equivalent; or maybe your are (were) claiming
that, and this is what you mean by “range” of a verb?  The latter
concept still puzzles me; I searched the entire dictionary but I did
not find anything relevant; a clarification would be welcome.

In any case, one could write a sentence, that could be the core of an
adverb or conjunction, to show the (indefinite) integrals and
derivatives of composition of verbs (plot @: (] ; |: @: ((u @ v)  d.
_2 _1 0 1 2))).  For instance,

   u=. -:
   v=. *:

   Y=. _2 + 0.01 * i.401

   load'plot'

   plot @: (] ; |: @: ((u @ v)  d. _2 _1 0 1 2)) Y

If, for whatever reason, somebody (Linda for example?) would like to
use (at) and ([:) instead of (@) and (@:) a simple replacement of (@)
by (at) unfortunately would not work,

   ([: plot ] ; [: |:  (u at v) d. _2 _1 0 1 2)  Y
|domain error
|       ([:plot];[:|:(u at v)d._2 _1 0 1 2)Y
|[-11]

Should the replacement have worked?  In other words, is the different
treatment of (@) and (at) by (d.) a bug rather than a feature?  I
strongly suspect the answer is yes.  Why?

   plot @: (] ; |: @: ((u @: v) d. _2 _1 0 1 2)) Y
   plot @: (] ; |: @: (([: u v) d. _2 _1 0 1 2)) Y
|domain error
|       plot@:(];|:@:(([:u v)d._2 _1 0 1 2))Y
|[-2]

Which also reinforces my aversion to ([:).


On Thu, Jan 10, 2013 at 7:05 PM, Raul Miller <[email protected]> wrote:
> If v1 and v2 are verbs then v1 at v2 presents verb definitions of at.
> These definitions of course incorporate the definitions of v1 and v2.
>
> That said, you are right and I should have explicitly included its
> conjunction definition, and some of my examples were broken, and your
> suggested alternatives address this brokenness.
>
> Thanks,
>
> --
> Raul
>
> On Thu, Jan 10, 2013 at 6:49 PM, Jose Mario Quintana
> <[email protected]> wrote:
>> Do you mean by "verb definition" and “of the verb” a generic (u at v)
>> verb? (I am somewhat confused because you initially wrote "Here's a
>> definition for at" which is a definition of a conjunction.)  If so, I
>> understand what you mean by domain, mapping (at least for verbs that
>> are meant to be functions) and rank; however, what do you mean by
>> "range"?
>>
>> I do not know exactly what you mean by "at d. 1" and "@ d.1" perhaps
>> ((u at v) d.1) and ((u @ v) d.1)?
>>
>> On Thu, Jan 10, 2013 at 10:57 AM, Raul Miller <[email protected]> wrote:
>>>
>>> By "definition" I specifically mean "verb definition" which means: the
>>> behavior (domain, range, rank, mapping) of the verb in the monadic
>>> case and the dyadic case.  Also, in the general case "definition"
>>> would also include any noun, adverb or conjunction definitions.
>>>
>>> In this case, the verb definition of 'at' is used only within the
>>> context of the d. definition -- to make at d. 1 and @ d. 1 be
>>> identical we would need to fix the definition of d.
>>>
>>> --
>>> Raul
>>>
>>> On Wed, Jan 9, 2013 at 5:37 PM, Jose Mario Quintana
>>> <[email protected]> wrote:
>>> > Sure, if you do not make use of d. is insignificant. However, difference 
>>> > in
>>> > behavior because of context could cause a production system to crash and
>>> > that would be very significant to me; being extra careful (trust but
>>> > verify), in my experience, has prevented grim consequences in similar
>>> > circumstances.
>>> >
>>> > I am curious: What you do exactly mean by "Here's a definition for at 
>>> > which
>>> > works exactly like @"?
>>> >
>>> > On Fri, Jan 4, 2013 at 11:00 AM, Raul Miller <[email protected]> 
>>> > wrote:
>>> >> On Thu, Jan 3, 2013 at 5:53 PM, Jose Mario Quintana
>>> >> <[email protected]> wrote:
>>> >>>> Here's a definition for at which works exactly like @
>>> >>>>
>>> >>>>    at=: 2 :'([: u v)"v
>>> >>>
>>> >>>
>>> >>> Rather works almost exactly?
>>> >>>
>>> >>>    ('*'"_) @ ((+: @ *:) (d.1)) (0 1 2)
>>> >>> *
>>> >>>    ('*'"_) @ ((+: at *:) (d.1)) (0 1 2)
>>> >>> ***
>>> >>>
>>> >>>    ((+: @ *:) (d.1)) b.0
>>> >>> _ _ _
>>> >>>    ((+: at *:) (d.1)) b.0
>>> >>> 0 0 0
>>> >>
>>> >> Here, we are no longer comparing the definitions of @ and at
>>> >>
>>> >>    ((+: @ *:) (d.1))
>>> >> 0 4x&p.
>>> >>    ((+: at *:) (d.1))
>>> >> 0 4x&p."0 0 0
>>> >>
>>> >> Instead, it's the working of d. that is significant here.
>>> >>
>>> >> Here's another case where @ and at are different, and I feel that the
>>> >> significance of this case is similar to the significance of the d.
>>> >> case (though obviously they are not identical cases):
>>> >>
>>> >>    '@' -: 'at'
>>> >> 0
>>> >>
>>> >> --
>>> >> Raul
>>> >> ----------------------------------------------------------------------
>>> >> For information about J forums see http://www.jsoftware.com/forums.htm
>>> > ----------------------------------------------------------------------
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>>> ----------------------------------------------------------------------
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>> ----------------------------------------------------------------------
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