From:  Rosario19 <Ros@invalid.invalid>
Date:  07 Jul 2019 23:01:47 Hong Kong Time
Newsgroup:  news.alt119.net/comp.lang.apl
Subject:  

Re: NARS and in set instruction

NNTP-Posting-Host:  null

On Sun, 7 Jul 2019 10:15:02 -0400, Rav wrote:

>On 7/7/2019 9:59 AM, Rosario19 wrote:
>> On Sun, 07 Jul 2019 09:20:39 +0200, Rosario19  wrote:
>> 
>>> in the old version of Nars
>>>       (»1 3)­»1 2
>>> 0
>>>
>>> in the new version of Nars
>>>       (»1 3)­»1 2
>>> 1
>> 
>> just above i not understand...
>> 
>> » is enclose, ­ is "in" set
>> 
>> for the old version of Nars:
>> 
>>              (»1 2)­,»1 2
>> 1
>> 
>> ok this is right because ,»1 2 is a list or a set
>> 
>>              (»1 2)­»1 2
>> 1
>> 
>> not seems right because »1 2 it seems a scalar...
>> a scalar is a list or a set?
>> 
>> reference
>> 
>>        ?fmt »1 2
>> +------+
>> ¦+2---+¦
>> ¦¦ 1 2¦¦
>> ¦+~---+2
>> +?-----+
>> 
>> this seems to me a scalar...
>> 
>>        ?fmt ,»1 2
>> +1-----+
>> ¦+2---+¦
>> ¦¦ 1 2¦¦
>> ¦+~---+2
>> +?-----+
>> 
>> yes for Apl a scalar is a list...
>> 
>>        'a'­'a'
>> 1
>>        'a'­,'a'
>> 1
>> 
>> but in set teory one element can not be in itsefl
>> because it generate contraddiction in the theory...
>> 
>
>Perhaps think of it this way:
>
>(?1 2) ? This is a scalar
>((1 2)(1 3)) This is a two-element vector containing two scalars
>(,?1 2) ? This is a one-element vector containing one scalar

>In the third case, the scalar (?1 2) is still there, but is now one 
>element of a vector (a one-element vector).
>
>So when using ? (element of), you are asking if the scalar (?1 2) exists 
>anywhere in the right argument.  In all the three cases above, it does, 
>so the result is 1.  

i not agree in the case 1, 

      (/enclose 1 2)/in(/enclose 1 2)
1
      ?fmt (?1 2)
+-----+
¦+2--+¦
¦¦1 2¦¦
¦+~--+2
+?----+


for math (if "e" is "\in" as element of set) 

{1}e{{1}} {1}e{{1},{2}}  1e{1}

are all ok, but never

{1}e{1} or 1e1 or {1}e{ {{1}} }

all false and not in the axioms
so epsilon /in in APL is not the /in in the logic math theory...

>It doesn't matter whether the right argument is a 
>vector ("list") or not, it only matters if the item(s) in the left 
>argument appear at least once anywhere in the right argument.  The right 
>argument (and even the left argument for that matter) can be a scalar, a 
>vector, a matrix, or any higher-dimension array.
>
>What do you think the result of this should be:  (?1 2)?4 3?(1 3)(1 2)

above should return true because 1 2 enclosed is in the matrix as
element

>Or this:  (1 2)(3 4)(1 3)?4 3?(1 3)(1 2)

above return 1 0 1