Hack + Computed Goto = Leightweigh C_OR (Was: Vanilla Prolog: semi-decidable =\= decidable)

From	Mild Shock <janburse@fastmail.fm>
Newsgroups	comp.lang.prolog
Subject	Hack + Computed Goto = Leightweigh C_OR (Was: Vanilla Prolog: semi-decidable =\= decidable)
Date	2026-07-04 16:58 +0200
Message-ID	<112b732$20pmt$1@solani.org> (permalink)
References	<vq4a7g$10843$1@solani.org> <10p4dif$1nve7$1@solani.org>

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Hi,

pi-WAM is a nice challenge, since its aim is to go
even blow the instruction set of SWI-Prolog,
while only using a Hack variant as instruction

stream. But what is Hack? Well Hack seems to be
the missing legacy of Niclaus Wirths PL0. The
Hack (machine .asm) and Jack (highlevel compiler

generating .vm which can be converted to .asm)
combo makes even the famous Crafting Interpreters
/Lox by Bob Nystrom redundant:

Nand to Tetris courses are taught at 400+
universities, high schools, and bootcamps. The
students who take them range from high
schoolers to Ph.D. students to
https://www.nand2tetris.org/

But digging deaper in Hack, it has no functions
pointers so objects don't use virtual tables.
But what will pi-WAM need and that is not yet

in Hack? Given that my pi-WAM doesn't want a stack
nor a choice point lists? Currently there is the
idea to add a computed goto and that it can

cover a more lightweight C_OR as known from
SWI-Prolog, that would have the C_OR branches
maybe restricted to have no outside

clause calls? Lets see. Not yet sure.

Bye

Mild Shock schrieb:
> Hi,
> 
> Somebody just changed the Vanilla Prolog
> meta interpreter from:
> 
> solve(true) :- !.
> solve((A,B)) :- !, solve(A), solve(B).
> solve(H) :- clause(H, B), solve(B).
> 
> Into a cycle checking interpreter. It makes
> certain Datalog programs and queries complete,
> but it doesn't make Horn clauses complete:
> 
> solve(A) :- solve(A, []).
> 
> solve(true, _) :- !.
> solve((A,B), L) :- !, solve(A, L), solve(B, L).
> solve(A, L) :- member(B, L), A =@= B, !, fail.
> solve(H, L) :- clause(H, B), solve(B, [H|L]).
> 
> Bye
> 
> P.S.: Here is a proof for Datalog:
> 
> Since Datalog has only constants and variables,
> no function symbols at all, there are only finitely
> many literals at runtime modulo (=@=)/2.
> 
> Q.E.D.
> 
> dart200 schrieb:
>  > The following claim from p246 of Turing’s seminal paper On Computable 
> Numbers is a fallacy:
>  >
>  > /the problem of enumerating computable sequences is equivalent to the 
> problem of finding out whether a given number is the D.N of a circle- 
> free machine, and we have no general process for doing this in a finite 
> number of steps/
>  >
>  > For any given computable sequence, there are _infinite_ circle-free 
> machines which compute that particular sequence. Not only can various 
> machines differ significantly in the specific steps to produce the same 
> output, machines can be changed in superficial ways that do not 
> meaningfully affect the steps of computation, akin to modern no-op 
> statements or unreachable code
>  >
>  > The problem of enumerating computable sequences, however, only 
> depends on successfully identifying _one_ circle-free machine that 
> computes any given computable sequences. While identifying more than one 
> can certainly be done, it is _not_ a requirement for enumerating 
> computable sequences, as _one_ machine computing a sequence /suffices to 
> output any and all digits of that sequence/
>  >
>  > The problem of enumerating computable sequences is therefore _not_ 
> actually equivalent to a _general process_ of enumerating circle-free 
> machines, as there is no need to identify all circle-free machines which 
> compute any given computable sequence
>  >
>  > Said problem is only equivalent to a _limited process_ of enumerating 
> circle-free machines. The machine which identifies circle-free machines 
> only needs the limited power of determining _at least one_ circle-free 
> machine for any given computable sequence, _not all_ machines for any 
> given computable sequence
>  >
>  > Because of this fallacy, the proof found on the following p247, where 
> an ill-defined machine 𝓗 (which attempts and fails to compute the 
> direct diagonal β’) is found to be undecidable in respect to circle-free 
> decider 𝓓; does not then prove an impossibility for enumerating 
> computable sequences. As the problem of enumerating /all circle-free 
> machines/ is _not_ equivalent to that of enumerating /just computable 
> sequences/
>  >
>  >
> 
> Mild Shock schrieb:
>> Concerning this boring nonsense:
>>
>> https://book.simply-logical.space/src/text/2_part_ii/5.3.html#
>>
>> Funny idea that anybody would be interested just now in
>> the year 2025 in things like teaching breadth first
>> search versus depth first search, or even be “mystified”
>> by such stuff. Its extremly trivial stuff:
>>
>> Insert your favorite tree traversal pictures here.
>>
>> Its even not artificial intelligence neither has anything
>> to do with mathematical logic, rather belongs to computer
>> science and discrete mathematics which you have in
>> 1st year university
>>
>> courses, making it moot to call it “simply logical”. It
>> reminds me of the idea of teaching how wax candles work
>> to dumb down students, when just light bulbs have been
>> invented. If this is the outcome
>>
>> of the Prolog Education Group 2.0, then good night.
>>
>

Thread

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              Head to Head Race with Scryer Prolog (Was: WebPL is an interesting project) Mild Shock <janburse@fastmail.fm> - 2025-08-17 18:24 +0200
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  Vanilla Prolog: semi-decidable =\= decidable (Re: Prolog Education Group clueless about the AI Boom?) Mild Shock <janburse@fastmail.fm> - 2026-03-14 20:40 +0100
    Its on the Internet, so it must be true? (Was: Vanilla Prolog: semi-decidable =\= decidable) Mild Shock <janburse@fastmail.fm> - 2026-03-16 11:01 +0100
    Hack + Computed Goto = Leightweigh C_OR (Was: Vanilla Prolog: semi-decidable =\= decidable) Mild Shock <janburse@fastmail.fm> - 2026-07-04 16:58 +0200
      The stack and choice points as an after match (Re: Hack + Computed Goto = Leightweigh C_OR) Mild Shock <janburse@fastmail.fm> - 2026-07-04 17:07 +0200
        Introduction to AI Accelerator Prolog [π-WAM of Dogelog] (Was: The stack and choice points as an after match) Mild Shock <janburse@fastmail.fm> - 2026-07-17 10:49 +0200
          Not praying to the god of lambda calculus [π beats α] (Was: Introduction to AI Accelerator Prolog [π-WAM of Dogelog]) Mild Shock <janburse@fastmail.fm> - 2026-07-17 11:13 +0200
          pi in pi-WAM refers to pi-calculus (Re: Introduction to AI Accelerator Prolog [π-WAM of Dogelog]) Mild Shock <janburse@fastmail.fm> - 2026-07-18 01:22 +0200
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              Robin Milners pi calculus is typeless (Re: Milners fickle() in pi-WAM [For fun and profit]) Mild Shock <janburse@fastmail.fm> - 2026-07-18 11:00 +0200
                Can the Church Turing hypotheses be refuted? [TLo @ FOM] (Re: Robin Milners pi calculus is typeless) Mild Shock <janburse@fastmail.fm> - 2026-07-18 11:10 +0200
          Accelerate Lean! From Theorem 3.11 to Corollary 3.12 [ZMC] (Was: Introduction to AI Accelerator Prolog [π-WAM of Dogelog]) Mild Shock <janburse@fastmail.fm> - 2026-07-19 16:06 +0200
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