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3.5.3.4. "Translating" from NL into Conceptual Format

We will only mention here, very briefly, the NL/NKRL "translation" procedures. The equivalent procedures used in a CGs context are not fundamentally different, in essence, from those that will be expounded here.

The NL/NKRL (and NL/CGs) translation procedures are based on the well-known principle of locating, within the original texts, the syntactic and semantic indexes that can evoke the conceptual structures used to represent these texts. The specific NKRL contribution has consisted, in particular, in the set-up of a rigorous algorithmic procedure, centered around the two following conceptual tools:

  • The use of rules -- evoked by particular lexical items in the text examined and stored in proper conceptual dictionaries -- that take the form of generalized production rules. The left-hand side (antecedent part) is always a syntactic condition, expressed as a fragment of tree-like structure, which must be unified with the results of the general parse tree produced by the syntactic specialist of the translation system (see also the rules in Table 3 above). If the unification succeeds, the right hand sides (consequent parts) are used, e.g., to generate well-formed templates ("triggering rules").
  • The use, within the rules, of advanced mechanisms to deal with the variables. For example, in the specific "triggering" family of NKRL rules, the antecedent variables (a-variables) are first declared in the syntactic (antecedent) part of the rules, and then "echoed" in the consequent parts, where they appear under the form of arguments and constraints associated with the roles of the activated templates. Their function is that of "capturing" -- during the match between the antecedents and the results of the syntactic specialist -- NL or H_CLASS terms to be then used as specialisation terms for filling up the activated templates and building the final NKRL structures.
trigger: "call"

syntactic condition:
(s (subj (np (noun x1)))
   (vcl (voice active) (t = x2 = call))
   (dir-obj
      (np (modifiers (adjs x31))
        (noun x3)
        (modifiers (pp (prep about | concerning | ... )
          (np (noun x4)
          (modifiers (pp (prep of | for ...)
            (np (noun x5))))))))))
parameters for the template:

(PRODUCE4.12 (roles subj x1 obj (SPECIF x2 (SPECIF x3 x31)) +topic (specif x4 x5)) (constr x3 assembly_ x31 quality_ x5 modification_procedures))

FIGURE 21 An example of NKRL triggering rule.

A detailed description of these tools can be found, e.g., in (Zarri, 1995). We reproduce now, Figure 21, one of the several triggering rules to which the lexical entry "call" -- pertaining to the fragment of news story, "the financial daily Il Sole 24 Ore reported ...," examined in the previous subsection -- contains a pointer, i.e., one of the rules corresponding to the meaning "to issue a call to convene." This rule allows the activation of a basic template (PRODUCE4.12) giving rise, at a later stage, to the occurrence c2 of Figure 18 before; the x symbols in Figure 21 correspond to a-variables.

We can remark that all the details of the full template are not actually stored in the consequent, given that the H_TEMP hierarchy is part of the "common shared data structures" used by the translator. Only the parameters relating to the specific triggering rule are, therefore, really stored. For example, in Figure 21, the list "constr" specializes the constraints on some of the variables, while others -- e.g., the constraints on the variables x1 (human_being/social_body) and x4 (planning_activity) -- are unchanged with respect to the constraints permanently associated with the variables of template PRODUCE4.12.

Please note that techniques like these, even when they can be associated with large knowledge bases of rules in the style of that shown in Figure 21, cannot guarantee that they will allow the translation into conceptual format to be carried out in a completely automated (and correct) way. This sort of procedures require then, always, some sort of human intervention -- excepting in all those cases (categorization, abstracting, etc.) where some sort of rough (and also partially erroneous) analysis can be tolerated.


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