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Corr. (Was: Wait till they find out about compare/3)

From Mild Shock <janburse@fastmail.fm>
Newsgroups comp.lang.prolog
Subject Corr. (Was: Wait till they find out about compare/3)
Date 2025-07-15 15:28 +0200
Message-ID <1055l2j$2ac8t$1@solani.org> (permalink)
References <104o5kc$20fno$1@solani.org> <104qf0n$21rh6$1@solani.org> <1055ki3$2abt8$1@solani.org> <1055kpn$2ac5o$1@solani.org>

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Corr.: Small typo in the number
expansion itself, should read:

10/81 = 0.(123456790) = 0.12345679(012345679)

Mild Shock schrieb:
> 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.
>>>>
>>>
>>
>

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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
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          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
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  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
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              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
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                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

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