Wait till they find out about compare/3 (Was: The headache an eGovernment might get from Prolog)

From	Mild Shock <janburse@fastmail.fm>
Newsgroups	comp.lang.prolog
Subject	Wait till they find out about compare/3 (Was: The headache an eGovernment might get from Prolog)
Date	2025-07-15 15:24 +0200
Message-ID	<1055kpn$2ac5o$1@solani.org> (permalink)
References	<104o5kc$20fno$1@solani.org> <104qf0n$21rh6$1@solani.org> <1055ki3$2abt8$1@solani.org>

Show all headers | View raw

Hi,

Now somebody was so friendly to spear head
a new Don Quixote attempt in fighting the
windmills of compare/3. Interestingly my

favorite counter example still goes through:

?- X = X-0-9-7-6-5-4-3-2-1, Y = Y-7-5-8-2-4-1,
    compare_with_stack(C, X, Y).
X = X-0-9-7-6-5-4-3-2-1,
Y = Y-7-5-8-2-4-1,
C = (<).

?- H = H-9-7-6-5-4-3-2-1-0, Z = H-9-7-6-5-4-3-2-1, Y = Y-7-5-8-2-4-1,
    compare_with_stack(C, Z, Y).
H = H-9-7-6-5-4-3-2-1-0,
Z = H-9-7-6-5-4-3-2-1,
Y = Y-7-5-8-2-4-1,
C = (>).

?- H = H-9-7-6-5-4-3-2-1-0, Z = H-9-7-6-5-4-3-2-1, X = 
X-0-9-7-6-5-4-3-2-1,
    compare_with_stack(C, Z, X).
H = H-9-7-6-5-4-3-2-1-0,
Z = X, X = X-0-9-7-6-5-4-3-2-1,
C = (=).

I posted it here in March 2023:

Careful with compare/3 and Brent algorithm
https://swi-prolog.discourse.group/t/careful-with-compare-3-and-brent-algorithm/6413

Its based that rational terms are indeed in
some relation to rational numbers. The above
terms are related to:

10/81 = 0.(123456790) = 0.12345679(02345679)

Bye

Mild Shock schrieb:
> Hi,
> 
> That false/0 and not fail/0 is now all over the place,
> I don't mean in person but for example here:
> 
> ?- X=f(f(X), X), Y=f(Y, f(Y)), X = Y.
> false.
> 
> Is a little didactical nightmare.
> 
> Syntactic unification has mathematical axioms (1978),
> to fully formalize unifcation you would need to
> formalize both (=)/2 and (≠)/2 (sic!), otherwise you
> rely on some negation as failure concept.
> 
> Keith L. Clark, Negation as Failure
> https://link.springer.com/chapter/10.1007/978-1-4684-3384-5_11
> 
> You can realize a subset of a mixture of (=)/2
> and (≠)/2 in the form of a vanilla unify Prolog
> predicate using some of the meta programming
> facilities of Prolog, like var/1 and having some
> 
> negation as failure reading:
> 
> /* Vanilla Unify */
> unify(V, W) :- var(V), var(W), !, (V \== W -> V = W; true).
> unify(V, T) :- var(V), !, V = T.
> unify(S, W) :- var(W), !, W = S.
> unify(S, T) :- functor(S, F, N), functor(T, F, N),
>       S =.. [F|L], T =.. [F|R], maplist(unify, L, R).
> 
> I indeed get:
> 
> ?- X=f(f(X), X), Y=f(Y, f(Y)), unify(X,Y).
> false.
> 
> If the vanilla unify/2 already fails then unify
> with and without subject to occurs check, will also
> fail, and unify with and without ability to
> handle rational terms, will also fail:
> 
> Bye
> 
> Mild Shock schrieb:
>>
>> Interestingly, DCG is also affect. Here a
>> DCG take of an append app/3, it has the 2nd
>> and 3rd argument swapped:
>>
>> ?- [user].
>> app([]) --> [].
>> app([X|Y]) --> [X], app(Y).
>> ^D
>>
>> Looks like an append, taking the argument swap
>> into account, the A=B is redundant, could
>> be optimized away:
>>
>> /* SWI-Prolog 9.3.25 */
>> ?- listing(app/3).
>> app([], A, B) :-
>>      A=B.
>> app([A|B], [A|C], D) :-
>>      app(B, C, D).
>>
>> And works like an append, again taking the
>> argument swap into account:
>>
>> ?- app([1],X,[2,3]).
>> X = [1, 2, 3].
>>
>> Now the multi-argument indexing test, still
>> taking the argument swap into account;
>>
>> /* ECLiPSe Prolog 7.1beta #13 */
>> [eclipse 3]: app(X, [1], Y).
>>
>> X = []
>> Y = [1]
>> Yes (0.00s cpu, solution 1, maybe more) ? ;
>>
>> X = [1]
>> Y = []
>> Yes (0.00s cpu, solution 2)
>>
>> Versus:
>>
>> /* SWI-Prolog 9.3.25 */
>> ?- app(X, [1], Y).
>> X = [],
>> Y = [1] ;
>> X = [1],
>> Y = [] ;
>> false.
>>
>> Mild Shock schrieb:
>>> I am currently doing a re-evaluation of an old
>>> Prolog system, checking what features I could adopt.
>>> This is unlike the current trend where people have
>>> turned their focus on GUIs, like XPCE,
>>>
>>> or a are stuck in an endless loop of parser
>>> problems, like in Trealla. But I would nevertheless
>>> share my finding. Take this simple example of
>>> a list append:
>>>
>>> app([], X, X).
>>> app([X|Y], Z, [X|T]) :- app(Y, Z, T).
>>>
>>> ECLiPSe Prolog gives me, only one redo question
>>> in the top-level:
>>>
>>> /* ECLiPSe Prolog 7.1beta #13 */
>>> [eclipse 2]: app(X,Y,[1]).
>>>
>>> X = []
>>> Y = [1]
>>> Yes (0.00s cpu, solution 1, maybe more) ? ;
>>>
>>> X = [1]
>>> Y = []
>>> Yes (0.00s cpu, solution 2)
>>>
>>> In SWI-Prolog I find, two redo questions
>>> in the top.level:
>>>
>>> /* SWI-Prolog 9.3.25 */
>>> ?- app(X,Y,[1]).
>>> X = [],
>>> Y = [1] ;
>>> X = [1],
>>> Y = [] ;
>>> false.
>>>
>>> I know SWI-Prolog handles lists differently
>>> than other Prolog terms during indexing. Could
>>> this be the reason? Or maybe that the call is
>>> not “hot” enough, so it doesn’t get JIT-ed.
>>>
>>> ECLiPSe Prolog does it on the very first call,
>>> and I assume its due to a kind of index on
>>> the 3rd argument.
>>>
>>
>

Thread

The Ghosts in my Cabinet: Indexing Mild Shock <janburse@fastmail.fm> - 2025-07-10 12:45 +0200
  Observed while watching FAIL/REDO ports (Was: The Ghosts in my Cabinet: Indexing) Mild Shock <janburse@fastmail.fm> - 2025-07-10 12:46 +0200
    Shocking Revelation: No eGovernment can trust Prolog! (Was: Observed while watching FAIL/REDO ports) Mild Shock <janburse@fastmail.fm> - 2025-07-10 13:26 +0200
      Easier certification with 100% Prolog Prolog? (Was: Shocking Revelation: No eGovernment can trust Prolog!) Mild Shock <janburse@fastmail.fm> - 2025-07-10 14:05 +0200
        Doing a Prolog system without any iterator API (Was: Easier certification with 100% Prolog Prolog?) Mild Shock <janburse@fastmail.fm> - 2025-07-10 14:14 +0200
          The headache with JIT indexing: Native -> Prolog (Was: Doing a Prolog system without any iterator API) Mild Shock <janburse@fastmail.fm> - 2025-07-10 14:40 +0200
            Just lets burn another candle for Barty Boy (Was: The headache with JIT indexing: Native -> Prolog) Mild Shock <janburse@fastmail.fm> - 2025-07-10 18:13 +0200
              Physics PhDs might never have heard of Quantifier Eliminations (Re: Just lets burn another candle for Barty Boy) Mild Shock <janburse@fastmail.fm> - 2025-07-10 18:33 +0200
                How long willl I piss on Bart Demoen (Was: Physics PhDs might never have heard of Quantifier Eliminations) Mild Shock <janburse@fastmail.fm> - 2025-07-10 18:39 +0200
                But I shouldn't waste too much time (Was: How long willl I piss on Bart Demoen) Mild Shock <janburse@fastmail.fm> - 2025-07-10 19:13 +0200
  DCG is easily affected (Was: The Ghosts in my Cabinet: Indexing) Mild Shock <janburse@fastmail.fm> - 2025-07-11 09:38 +0200
    The headache an eGovernment might get from Prolog (Was: DCG is easily affected) Mild Shock <janburse@fastmail.fm> - 2025-07-15 15:20 +0200
      Wait till they find out about compare/3 (Was: The headache an eGovernment might get from Prolog) Mild Shock <janburse@fastmail.fm> - 2025-07-15 15:24 +0200
        Corr. (Was: Wait till they find out about compare/3) Mild Shock <janburse@fastmail.fm> - 2025-07-15 15:28 +0200
          eGovernements will need AGI to survive (Was: Corr. (Was: Wait till they find out about compare/3)) Mild Shock <janburse@fastmail.fm> - 2025-07-15 18:41 +0200
            Having 2544 issues is probably a bad sign (Re: eGovernements will need AGI to survive) Mild Shock <janburse@fastmail.fm> - 2025-07-15 18:41 +0200
              The Signal Collapse gives us System Uncertainty (Re: Having 2544 issues is probably a bad sign) Mild Shock <janburse@fastmail.fm> - 2025-07-15 19:02 +0200
                Rename GitHub, to TurdPit, and make Amber Heard their CEO (Was: The Signal Collapse gives us System Uncertainty) Mild Shock <janburse@fastmail.fm> - 2025-07-15 19:52 +0200
            Humans are just overwhelmed by computers (Was: eGovernements will need AGI to survive) Mild Shock <janburse@fastmail.fm> - 2025-07-16 18:59 +0200
              Fishy 🐟 in Scryer Prolog and SWI-Prolog (Was: Humans are just overwhelmed by computers) Mild Shock <janburse@fastmail.fm> - 2025-07-16 20:08 +0200
                So we are essentially all using Trojan Horses 🐎 daily? (Re: Fishy 🐟 in Scryer Prolog and SWI-Prolog) Mild Shock <janburse@fastmail.fm> - 2025-07-17 10:57 +0200
                Strudel Rust gives Scryer Frust 💩: Try C+20 Pipes (Was: Fishy 🐟 in Scryer Prolog and SWI-Prolog( Mild Shock <janburse@fastmail.fm> - 2025-11-25 22:55 +0100
              SWI-Prolog as a Test Bed for Copilots (Was: Humans are just overwhelmed by computers) Mild Shock <janburse@fastmail.fm> - 2025-07-20 14:36 +0200
                Mathematics currently hates Computer Science because of AI (Re: SWI-Prolog as a Test Bed for Copilots) Mild Shock <janburse@fastmail.fm> - 2025-07-20 15:13 +0200

csiph-web