LkbGeneration

This page was adapted from JacyGeneration by MichaelGoodman, and therefore many of the examples are from the [wiki:JacyTop JACY] Grammar.

TableOfContents

Overview

Described below is generation using the mtr rule formalism developed in the LOGON project.

Three files control the process mt.lsp, mtr.lsp and trigger.mtr. They are loaded by the script file.

Generating Semantically Empty Lexical Entries (trigger.mtr)

This file controls when to add lexical entries with empty semantics to the generator chart. If they were all added all the time then the chart would get too big.

• example of a rule for the past tense ending:

ta-end_gr := arg0e_gr &
[ CONTEXT [ RELS <! [ ARG0.E.TENSE past ] !> ],
  FLAGS.TRIGGER "ta-end" ].

• example of a rule for copulas:

-- You can use regular expressions in the strings: "~.*_a_"

;; should use lexical type for na-adj
na-cop-lex_gr := arg0e_gr &
[ CONTEXT [ RELS <! [ PRED "~.*_a_"] !> ],
  FLAGS.TRIGGER "na-cop-lex" ].

• Example of a case marker:

 ;;; ARG1 is ga
ga_gr_1 := arg0e_gr &
[ CONTEXT [ RELS <!  [ ARG0.E.PASS -, ARG1 individual & #i ] !> ],
  FLAGS [SUBSUME < #i >,
         TRIGGER "ga" ]].

How to list semantically empty lexical entries

;;;
;;; automatically generate rules for all semantically empty lexical entries
;;; which don't already have trigger rules
;;;
 (loop
     with *package* = (find-package :lkb)
     for id in mrs::*empty-semantics-lexical-entries*
     do
     (unless (or #+:mt
                 (gethash id mt::*transfer-triggers*)
                 (member id mrs::*gen-rule-ids*))
       (format
        t
        "~(~a~)_gr := generator_rule &~%~
         [ CONTEXT [ RELS <! [ PRED \"non_existing_rel\" ] !> ],~%  ~
           FLAGS.TRIGGER \"~(~a~)\" ].~%~%"
        id id)))
;;;                              (25-dec-04; oe, 13-Jun-06 FCB)

This produces trigger rules of the form:

tomae_numcl_gr := generator_rule &
[ CONTEXT [ RELS <! [ PRED "non_existing_rel" ] !> ],
  FLAGS.TRIGGER "tomae_numcl" ].

which should go into the trigger.mtr file until you decide how to trigger them..

ToDo

• It would be nice to be able to access the grammar's type hierarchy when writing trigger rules.

Blocking Generation (globals.lisp)

You can block generation of non-empty predicate by putting it in the list *duplicate-lex-ids* in globals.lisp. [wiki:JacyTop Jacy] currently does this to block informal and variant forms for which we have no available filter. Note that this is a list of lex-ids, not predicate names.

(setf *duplicate-lex-ids*
  '(;; s-end1-decl-lex - emphatic sentence enders
    ga-sap keredomo-send kedomo-send ga-sap kedo-send shi-send
    yo-2 yo-3 keredo-send exclamation-mark ze zo zo-2
    ;; s-end1-decl-minusahon-lex - emphatic sentence enders
    i-emp
    ;; variant forms of numbers (hankaku)
    zero_card_a one_card_a two_card_a three_card_a four_card_a
    five_card_a six_card_a seven_card_a eight_card_a nine_card_a
    ;; variant forms of numbers (zenkaku)
    zero_card one_card two_card three_card four_card
    five_card six_card seven_card eight_card nine_card
    ;;; indefinite pronouns FIXME - improve semantics
    donna douiu dono-det
    ))

You can also block rules from being used in generation by adding them to *gen-ignore-rules*, also in globals.lisp.

(setf *gen-ignore-rules*
  '(punct_bang_orule)

Other Notes

Make generation faster (globals.lsp)

(setf *gen-packing-p* t)
(setf *gen-filtering-p* t)
(setf *packing-restrictor*  '(RELS HCONS ORTH STEM RULE-NAME))

Fixup MRS (mrsglobals.lsp)

Reload generation rules without reindexing

This is useful when you are debugging.

(progn
  (mt:initialize-transfer)
  (mt:read-transfer-rules
   (list
    "~/delphin/grammars/japanese/generation.mtr")
   "Generator Triggger Rules"
   :filter nil :task :trigger :recurse nil :subsume nil))

MRS Semantic Equivalence Check

At the end of generation, the lkb checks that the MRS of the generated string is subsumed by the input MRS. That is, it contains all the information in the input. You can omit the check entirely by setting *bypass-equality-check* to t. You can relax the check by setting the post-generation semantic equivalence check to filter mode, i.e. prefer results that satisfy the test when available, but if no outputs pass the equivalence test at all, then output all complete generator results. This is set in lkb/globals.lsp.

; output all complete generated results
(setf *bypass-equality-check* t)

; prefer results with MRS subsumed by the input
; but if none exist then output all complete generated results
(setf *bypass-equality-check* :filter)

Checking the Generator Index

You can manually see if a predicate is on the generator's index with the following command:

(gethash "_inu_n_rel" mrs::*relation-index*)

Where _inu_n_rel is the relation name.