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From: wij <wyniijj5@gmail.com>
Newsgroups: comp.lang.c++
Subject: Re: Is this program OOP?
Date: Wed, 11 Dec 2024 01:02:15 +0800
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On Tue, 2024-12-10 at 17:04 +0100, David Brown wrote:
> On 10/12/2024 10:23, wij wrote:
> > On Mon, 2024-12-09 at 22:15 -0800, Tim Rentsch wrote:
> > > wij <wyniijj5@gmail.com> writes:
> > >=20
> > > > On Mon, 2024-12-09 at 09:35 -0800, Tim Rentsch wrote:
> > > >=20
> > > > > wij <wyniijj5@gmail.com> writes:
> > > > >=20
> > > > > > Because I said:=C2=A0 C++ is the best language to model general
> > > > > > problems.=C2=A0 So it is.
> > > > > >=20
> > > > > > Almost all are logical propositions.=C2=A0 Except those few key=
words,
> > > > > > such programwon't be recognized as a C++ program, instead of so=
me
> > > > > > kind of declarative language.
> > > > > >=20
> > > > > > Zebra puzzle is an interesting programing exercise because it i=
s
> > > > > > not too easy and also not too difficult.
> > > > > >=20
> > > > > > ------------
> > > > > > /* Copyright is licensed by GNU LGPL, see file COPYING. by I.J.=
Wang 2023
> > > > > >=20
> > > > > > =C2=A0=C2=A0Example of solving the zebra puzzle by using propos=
itional logic.
> > > > > > =C2=A0=C2=A0Zebra Puzzle https://en.wikipedia.org/wiki/Zebra_Pu=
zzle
> > > > > >=20
> > > > > > [...]
> > > > > > */
> > > > > > #include <Wy.stdio.h>
> > > > > > #include <Sc/PropExpr.h>
> > > > > >=20
> > > > > > using namespace Wy;
> > > > > > using namespace Sc;
> > > > > >=20
> > > > > > [...]
> > > > >=20
> > > > > You're asking a question that cannot be answered because much or
> > > > > most of the program is in the two include files, which are not
> > > > > shown.
> > > > >=20
> > > > > As a general rule, when posting code there should be enough poste=
d
> > > > > so that readers can at least compile it.=C2=A0 In cases like the =
program
> > > > > asked about here, what is posted should be enough to both compile
> > > > > the program and run the generated executable.
> > > >=20
> > > > I thought nobody will be interested with the implement, and what
> > > > is shown should be enough for the moment.
> > >=20
> > > The point is that what was posted is not enough to answer the
> > > question of the Subject: line.
> > >=20
> > > > The Zebra Puzzle program has two version, a_puzzle_21.cpp (has
> > > > shown) takes too long to complete.=C2=A0 a_puzzle_2.cpp (736 lines,=
 too
> > > > long to post, I thought) is the realistic one written in way I
> > > > feel just solving the prolem is enough.
> > >=20
> > > I wrote a program in prolog to solve this puzzle.=C2=A0 The entire
> > > program is 60 lines long, including 13 blank lines.=C2=A0 It finds
> > > the solution in 0.03 seconds.=C2=A0 The program doesn't do anything
> > > fancy;=C2=A0 it pretty much just gives the listed conditions in the f=
orm
> > > of prolog rules, plus 20 lines to establish the structure of the
> > > information that is being sought.
> >=20
> > Very dubious, show us what you say is true.
> >=20
>=20
> Prolog is a language that is ideally suited to such problems.=20
> Basically, you give the language a bunch of objects and facts and=20
> relations about those objects, then you ask it questions about them.=20
> It's at least 35 years since I tried Prolog one afternoon, and that's=20
> exactly the kind of task I played with (though a bit smaller).

I know a bit of prolog,lisp (in DOS era). Strongly suspicious what Tim says=
..

> This is not a big problem in any language.=C2=A0 It's 5 characteristics f=
or=20
> each of 5 houses - that's 3125 possibilities.=C2=A0 Make a big array of=
=20
> booleans, initialised to true.=C2=A0 Run through the array and kill any=
=20
> combination that is contrary to one of the facts.=C2=A0 It might have bee=
n a=20
> worthy benchmark in 1962 but it should not be challenging to solve with=
=20
> modern machines.=C2=A0 (Of course it can still inspire interesting soluti=
ons=20
> and ways to express code in different languages.)

Not that simple, try it to know (your eye may fool you, just like with libw=
y).

a_puzzle_2.cpp (736 lines) was a random try in normal C++ programming
style. I did not try to optimize it. It took 3m22s.=20
a_puzzle_21.cpp has 178 lines, about 40 lines of comments, so 178-40=3D138 =
lines.
So, I have reason to doubt 60 lines of prolog can do the job. And most
importantly, the number of 0.03 seconds is too difficult to explain.
Prolog is not really a declarative language, you need to provide 'algorithm=
'
to 'compute' the answer. So, there is reason why 'prolog' program can run f=
aster.
But, unless there is some built-in mechanism in modern=C2=A0prolog to solve=
=C2=A0
Zebra-puzzle-like problem, 60 lines of codes is dubious to me
and even so, 0.03 seconds remains highly dubious.