Hi Linas!
Am Mittwoch, 26. Februar 2020 22:24:45 UTC schrieb linas:
>
> If you really need it to work in *all* cases, then something like this:
>
> (DefineLink
> (DefinedPredicate "is in state")
> (Lambda
> (VariableList (Variable "a") (Variable "b"))
> (Equal (Variable "a") (Get (State (Variable "b") (Variable
> "x"))))))
>
> which you would use like so:
>
> (cog-evaluate!
> (EvaluationLink (DefinedPredicate "is in state")
> (List (Concept "red light") (Concept "stop light"))))
>
> and that should work just fine. This might be overkill for what you are
> trying to do ... but it does work, and the intent is that, for complex
> situations, this is how you would do it.
>
What actually did work, was this:
someone = ConceptNode("bob")
has_crate = ConceptNode("has crate")
StateLink(someone, has_crate)
DefineLink(
DefinedPredicateNode("is in state"),
LambdaLink(
VariableList(VariableNode("target"), VariableNode("state")),
EqualLink(SetLink(ListLink(VariableNode("target"),
VariableNode("state"))), GetLink(StateLink(VariableNode("anything"),
VariableNode("state"))))))
query = EvaluationLink(DefinedPredicateNode("is in state"),
ListLink(someone, ConceptNode("has crate")))
results = evaluate_atom(atomspace, query)
print(results)
Notice the addition of the SetLink which is necessary as the GetLink
returns one.
Herein also lies the problem: This works fine if there is just one entity
with a given state, but it fails when there are multiple entities with a
given state because in this case the SetLink returned by the GetLink will
contain multiple ListLinks and so the EqualLink evaluates to (0, 1).
I tried to get around this using a SubSetLink, but that runs into a
NotImplemented error.
[2020-05-06 12:24:50:065] [ERROR] Either incorrect or not implemented yet.
Cannot evaluate (SubsetLink
(SetLink
(ListLink
(ConceptNode "bob" (stv 1.000000 1.000000)) ; [510da4194021b685][1]
(ConceptNode "has crate") ; [7f11eb3c16f8beb0][1]
) ; [8983ace7aae6590b][-1]
) ; [e7b63e6f2f3e7452][-1]
(GetLink
(StateLink
(VariableNode "anything") ; [7f082726ca4ddba3][1]
(VariableNode "state") ; [38680c2d1603e9c8][1]
) ; [df8079f1c9baf09d][-1]
) ; [9e4a50ee0b3b95e2][-1]
) ; [cf2ff93ac449180b][-1]
(/home/rasberry/git/atomspace/opencog/atoms/execution/EvaluationLink.cc:100)
Stack Trace:
2: basic_string.h:222 std::__cxx11::basic_string<char,
std::char_traits<char>, std::allocator<char> >::_M_is_local() const
3: Logger.cc:594 opencog::Logger::Error::operator()(char const*, ...)
4: exceptions.cc:54 opencog::StandardException::parse_error_message(char
const*, __va_list_tag*, bool)
5: exceptions.cc:82 opencog::StandardException::parse_error_message(char
const*, char const*, __va_list_tag*, bool)
6: exceptions.cc:169 opencog::SyntaxException::SyntaxException(char
const*, char const*, __va_list_tag*)
7: EvaluationLink.cc:100 _Z20throwSyntaxExceptionbPKcz()
8: basic_string.h:222 std::__cxx11::basic_string<char,
std::char_traits<char>, std::allocator<char> >::_M_is_local() const
9: EvaluationLink.cc:299 bool_to_tv()
10: EvaluationLink.cc:999
opencog::EvaluationLink::do_evaluate(opencog::AtomSpace*, opencog::Handle
const&, bool)
11: shared_ptr_base.h:729
std::__shared_count<(__gnu_cxx::_Lock_policy)2>::~__shared_count()
12: EvaluationLink.cc:868
opencog::EvaluationLink::do_eval_scratch(opencog::AtomSpace*,
opencog::Handle const&, opencog::AtomSpace*, bool)
13: EvaluationLink.cc:999
opencog::EvaluationLink::do_evaluate(opencog::AtomSpace*, opencog::Handle
const&, bool)
14: shared_ptr_base.h:758
std::__shared_count<(__gnu_cxx::_Lock_policy)2>::_M_swap(std::__shared_count<(__gnu_cxx::_Lock_policy)2>&)
15: [0x4bc9ba] ??() ??:0
16: [0x4ba036] ??() ??:0
17: [0x4eb32f] ??() ??:0
18: [0x4e5592] ??() ??:0
19: [0x4e3e46] ??() ??:0
20: [0x493ade] ??() ??:0
21: libc-start.c:325 __libc_start_main()
22: [0x4934a9] ??() ??:0
Traceback (most recent call last):
File "./example3.py", line 99, in <module>
results = evaluate_atom(atomspace, query)
File "opencog/bindlink.pyx", line 21, in opencog.bindlink.evaluate_atom
(/home/rasberry/git/atomspace/build/opencog/cython/opencog/bindlink.cpp:1268)
RuntimeError: Either incorrect or not implemented yet. Cannot evaluate
(SubsetLink
(SetLink
(ListLink
(ConceptNode "bob" (stv 1.000000 1.000000)) ; [510da4194021b685][1]
(ConceptNode "has crate") ; [7f11eb3c16f8beb0][1]
) ; [8983ace7aae6590b][-1]
) ; [e7b63e6f2f3e7452][-1]
(GetLink
(StateLink
(VariableNode "anything") ; [7f082726ca4ddba3][1]
(VariableNode "state") ; [38680c2d1603e9c8][1]
) ; [df8079f1c9baf09d][-1]
) ; [9e4a50ee0b3b95e2][-1]
) ; [cf2ff93ac449180b][-1]
(/home/rasberry/git/atomspace/opencog/atoms/execution/EvaluationLink.cc:100)
Do you have an idea on how to check for SetLink membership? Or am I doing
something wrong?
Best regards,
Alex
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