On 3/2/20 4:36 PM, Linas Vepstas wrote:
Suppose that the pattern matcher finds zero solutions to the original
query -- there is no combination of
human/picker/place1/origin/destination in the *current* atomspace that
satisfies that pattern. In this case, the backward chainer then examines
the set of rules that it has, to determine, if possible, whether there
is a sequence of deductions (a sequence of rule applications) that
provide suitable Atoms that allow your pattern to be satisfied. For
example, the current AtomSpace might not contain any humans at all, but
perhaps there is a way to infer that someone is human. Or a better
example: there is no (Evaluation (Predicate "leads to") origin
destination) but perhaps the backward chainer can find a sequence of
multiple steps that lead from origin to destination -- it can find a
path -- that eventually leads to a satisfaction of all of your terms.
Exactly.
The problem with path-finding, is, of course, that it's a hard problem:
there can be a combinatorial explosion, and thus an explosion of CPU
time. There are algorithms that, for example, know all about 2D space,
and make use of 2D geometry to find a good path. The backward chainer
has no clue that it's exploring a 2D space, so it's search for a path is
a bit more blind.
Correct.
Nil
Perhaps there's a way of making it clever, e.g. taking
the A*-search rules and turning them into a PLN formula, and maybe that
would work... but this discussion is not yet at this level.
--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 [email protected]
<mailto:[email protected]>.
To view this discussion on the web visit
https://groups.google.com/d/msgid/opencog/CAHrUA35gUeZhOLzDpYtDSrFXCAXSk8ueVEL5DRw2WRsRZuDxgQ%40mail.gmail.com
<https://groups.google.com/d/msgid/opencog/CAHrUA35gUeZhOLzDpYtDSrFXCAXSk8ueVEL5DRw2WRsRZuDxgQ%40mail.gmail.com?utm_medium=email&utm_source=footer>.
--
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 [email protected].
To view this discussion on the web visit
https://groups.google.com/d/msgid/opencog/f47caf61-8cbe-6577-e6ee-c70ec67864ca%40gmail.com.
