SuReal not handling Predicate without ListLink wrapping argument

[eddiemonroe]

My understanding is that Predicates with single arguments do not need a ListLink to wrap the argument, e.g.,

Evaluation
  Predicate "pred"
  Concept "argument"

If that is not correct, and the above is not a valid form, then this is not a bug and I take it back.

Otherwise, an Evaluation in the form above does not return a result in SuReal, while the same Evaluation with a List wrapping the argument does return a result.

This will reproduce the alleged bug:

(use-modules
  (opencog)
  (opencog exec)
  (opencog nlp)
  (opencog nlp chatbot)
  (opencog nlp relex2logic)
  (opencog nlp sureal))

(define with-list
  (EvaluationLink
     (PredicateNode "entertained")
     (ListLink
        (ConceptNode "you"))))

(define no-list
  (EvaluationLink
    (PredicateNode "entertained")
    (ConceptNode "you")))

(define (sureal-for-logic logic)
  (sureal
    (Set
      logic
      (Inheritance
        (InterpretationNode "blah")
        (DefinedLinguisticConcept "TruthQuerySpeechAct")))))

; pre-parse for sureal sentance generation 
(nlp-parse "Were you entertained?")

(format #t "\nWith List result:\n~a\n" (sureal-for-logic with-list))
(format #t "\nNo List result:\n~a\n\n" (sureal-for-logic no-list))

Results:

With List result:
((were you entertained ?))

No List result:
()

[leungmanhin]

Yes I think this is more about pattern matching, with-list and no-list are syntactically two different graphs after all, so the pattern matcher will not return the with-list one if the query has no list, and vice versa, e.g.

(use-modules
  (opencog)
  (opencog exec))

(EvaluationLink
  (PredicateNode "entertained")
  (ListLink
    (ConceptNode "you")))

(EvaluationLink
  (PredicateNode "entertained")
  (ConceptNode "they"))


(define with-list-query
  (GetLink
    (TypedVariableLink
      (VariableNode "$x")
      (TypeNode "ConceptNode"))
  (EvaluationLink
    (PredicateNode "entertained")
    (ListLink
      (VariableNode "$x")))))

(define no-list-query
  (GetLink
    (TypedVariableLink
      (VariableNode "$y")
      (TypeNode "ConceptNode"))
  (EvaluationLink
    (PredicateNode "entertained")
    (VariableNode "$y"))))


(format #t "\nWith List result:\n~a\n" (cog-execute! with-list-query))
(format #t "\nNo List result:\n~a\n\n" (cog-execute! no-list-query))

But I think this would not be a big problem since the current NLP pipeline generates a ListLink to wrap those arguments for every EvaluationLink, or maybe not?