Re: ?x => {...} rules (Re: N3 meeting - 12 pm (EDT) Monday 11 July)

On 12/07/2022 13:21, Doerthe Arndt wrote:
> Hi Pierre-Antoine,
>
>> Am 12.07.2022 um 13:02 schrieb Pierre-Antoine Champin 
>> <pierre-antoine@w3.org>:
>>
>> Great, thanks Jos.
>>
>> I just realized, however, that the example
>>
>>     ?x => { :a :b :c }
>>
>> could be made much more evil:
>>
>>     ?x => { :god :knows ?x }.
>>
>> (an inverted "simon says" example, if you like).
>>
>> Dörthe, I am not sure whether we discussed this one or not...
>> It seems to me that this one would generate an infinite number of 
>> triples, namely:
>>     :god :knows {}.
>>     :god :knows { :god :knows {} }.
>>     :god :knows { :god :knows { :god :knows {} } }.
>>     # and so on...
>>
>>
>
> We actually discussed exactly that example (remember that you 
> constructed something similar before and we discussed that it won’t 
> terminate because it keeps doing derivations?).
>>
>> However, contrarily to one might expect, it does not necessarily 
>> implies that god know everything that is true. E.g., in the current 
>> semantics,
>>
>>     :a :b :c.
>>     ?x => { :god :knows ?x }.
>>
>> does not entail, in my (possibly faulty) opinion
>>
>>     :god :knows { :a :b :c }.
>>
>> I am not quite comfortable with this... :-/
>>
>>
>
> It actually does produce :god :knows { :a :b :c }. If we assume that { 
> :a :b :c } is part of our terms.
But do we? It seems to me that this is not required by the current 
semantics, unless that quoted graph is used in some triple...
> In that sense, god will know everything which is expressible in our 
> language, i.e. all possible sets of triples which can be put into 
> quoted graphs.
> This example is of rather theoretical nature, since forward-rules like 
> the one you give above will not terminate. If we did the example 
> backwards like
>>
>>  :a :b :c.
>>   { :god :knows ?x } <=   ?x .
>>
> And a query { :god :knows { :a :b :c }.}=>{ :god :knows { :a :b :c }.}.
>
>  We should get :god :knows { :a :b :c }.
>
> But that is currently not the case in the online version of the editor.
>
> Kind regards,
> Dörthe
>
>>   pa
>>
>> On 11/07/2022 22:31, Jos De Roo wrote:
>>> As discussed in the meeting today 
>>> https://docs.google.com/document/d/1A3HAUhjaVnnJ6yVbFAvIBRJQjUY9aFlQ2_bGxkD0mnE/edit#

>>> EYE now supports the list:setEqualTo and list:setNotEqualTo 
>>> built-ins and the tests below all succeed:
>>>
>>> @prefix list: <http://www.w3.org/2000/10/swap/list#>.
>>> @prefix : <http://example.org/test#>.
>>>
>>> #:s :p :o.
>>> #?x => {:a :b :c}.
>>>
>>> {(:alice :bob :charlie) list:setEqualTo (:bob :charlie :alice)} => 
>>> {:test1 a :OK}.
>>> {(:alice :bob :charlie) list:setEqualTo (:alice :bob :charlie 
>>> :alice)} => {:test2 a :OK}.
>>> {(:alice :bob :charlie ?X) list:setEqualTo (:alice ?Y :bob 
>>> :charlie)} => {:test3 a :OK}.
>>> {(:alice :bob :charlie :dan) list:setNotEqualTo (:eve :bob :charlie 
>>> :alice)} => {:test4 a :OK}.
>>> {(:alice :bob :charlie ?X) list:setNotEqualTo (:alice ?Y :bob 
>>> :charlie ?Z)} => {:test5 a :OK}.
>>>
>>> Re the semantics discussion, it is now also the case that the rule
>>>
>>> ?x => {:a :b :c}.
>>>
>>> always gives
>>>
>>> :a :b :c.
>>>
>>> William, it would be nice if you could install the latest EYE 
>>> https://github.com/josd/eye/releases/tag/v22.0711.1846

>>> on your http://ppr.cs.dal.ca:3002/n3/editor/ or wherever you prefer ;-)
>>>
>>> Thanks for the constructive meeting today!
>>>
>>> Kind regards,
>>> Jos
>>>
>>> -- https://josd.github.io

>>>
>>>
>>> On Fri, Jul 8, 2022 at 4:29 PM William Van Woensel 
>>> <william.vanwoensel@gmail.com> wrote:
>>>
>>>     Hello everyone,
>>>
>>>     The next N3-dev community meeting will take place Monday 11 July
>>>     at 12:00 noon EDT (check your timezone
>>>     <https://www.timeanddate.com/worldclock/fixedtime.html?msg=Weekly+N3+WG+Skype+meeting&iso=20220711T12&p1=43&ah=1>).
>>>     Barring exceptional circumstances, this is the regular time for
>>>     meetings.
>>>     Please join the Skype group
>>>     <https://join.skype.com/aRBuOasYurPd> if you haven’t already!
>>>
>>>     You can find the proposed agenda (discussion topics), and prior
>>>     meeting notes, on the Google Doc
>>>     <https://docs.google.com/document/d/1A3HAUhjaVnnJ6yVbFAvIBRJQjUY9aFlQ2_bGxkD0mnE/edit?usp=sharing>.
>>>
>>>
>>>
>>>     Kind regards,
>>>
>>>     William
>>>
>> <OpenPGP_0x9D1EDAEEEF98D438.asc>
>