Linas,
On 5/31/19 8:19 AM, Linas Vepstas wrote:
> o ExistsLink, ForAllLink,
>
> These are legacy types; they are not used, at all. No one is
> implementing the sigma-pi Borel hierarchy in the atomspace. It seemed
> like a cool idea a decade ago, and they've mouldered ever since. They
> should probably be removed.
Not so fast, these links are used in PLN, well not in any practical
application ATM, but that should change in the future.
> PresentLink, AbsentLink---the implementation seems obvious from an
> outside perspective/at first glance.
>
>
> Hah hah. Two weeks ago, I sat down and rolled up my sleeves, and said to
> myself: "today is the day I implement AbsentLink as a C++ class". It's
> even mentioned in a comment in a recent commit. After laying the
> groundwork for this, I realized that it was impossible. Well, maybe not
I thought that AbsentLink implementation was nearly complete, and the
PresentLink implementation possibly already complete but requiring
more testing. I am not correct?
I intend to port all my Atomese code to use PresentLink, can I do so
already? I believe I can but your comment is casting some doubt.
Thanks,
Nil
> impossible, but very complicated and confusing, to the point that it
> seemed like a recipe for failure and wasted effort. A classical "bad
> idea". So I gave up.
>
> Though what could possibly "evaluating a SetLink" mean? ...)
>
>
> Oh! That's easy! Evaluate all of its members. I am on the verge of
> actually implementing that. I haven't, for two reasons:
>
> 1) no one is asking for this. There's no obvious need for it.
>
> 2) Different external theories might have their own distinct
> reason/answer to that question. For example, PLN states that one should
> use this-and-such formula to compute the resulting "average" truth
> value. But textbook Bayesian probability theory wants to supply you
> with a similar, but slightly different answer. And a neural net may
> want to provide yet another answer ... this is why Values exist (to
> accommodate all these theories), and it is also why "external code does
> things with atoms", instead of atoms having methods to do things. The
> C++ classes do not have a "Bayesian-probability" method, and a different
> "neural-net method", etc. ... on down the line.
>
> 3) Turns out SetLinks are evil. Who knew? Took years to figure this out,
> and not everyone understands yet. See the wiki page for SetLinks.
>
> -- Linas
>
> --
> cassette tapes - analog TV - film cameras - you
>
> --
> You received this message because you are subscribed to the Google
> Groups "opencog" group.
> To unsubscribe from this group and stop receiving emails from it, send
> an email to
opencog+u...@googlegroups.com
> <mailto:
opencog+u...@googlegroups.com>.
> To post to this group, send email to
ope...@googlegroups.com
> <mailto:
ope...@googlegroups.com>.
> Visit this group at
https://groups.google.com/group/opencog.
> To view this discussion on the web visit
>
https://groups.google.com/d/msgid/opencog/CAHrUA3521zp2cKL0ydEhuzb11Rc7JowcuVbPB_AYKW0jnM8vhw%40mail.gmail.com
> <
https://groups.google.com/d/msgid/opencog/CAHrUA3521zp2cKL0ydEhuzb11Rc7JowcuVbPB_AYKW0jnM8vhw%40mail.gmail.com?utm_medium=email&utm_source=footer>.
> For more options, visit
https://groups.google.com/d/optout.