Copyright (c) 2010 Aarne Ranta, under LGPL(3).
Part of MOLTO Project, WP 4.

Query language, based on the corpus from Ontotext.

Purpose: natural language queries to an ontology database.

Work in progress: 
- 19 June parsing 28% 160/562
- 17 June 2010 first version, parsing under 10%


The corpus contains misspellings and ungrammatical sentences; these will (mostly) not
be covered by the grammar.

Test:

  -- start GF with the grammar; notice that lib/present/ must have latest Eng libraries,
  -- which can be provided by 'runghc Make present lang api langs=Eng' in lib/src/
  % gf QueryEng.gf
  -- parse a sentence and see all variants
  > "p "Bulgarian people working at Google" | l -all

Regression test:

  -- run the parser on the corpus
  % gf QueryEng.gf <test.gfs > test.results8
  -- compute the number of sentences not covered
  % grep "no tree" test.results8 | wc


Semantics: generic logical semantics, that could be mapped to many query languages.
The denotations of the main categories are, assuming a domain of individuals:

  Set ;           P(P(D)) (generalized quantifier) -- the set requested, e.g. "all persons"
  Function ;      D -> P(D)   -- something of something, e.g. "subregion of Bulgaria"
  Kind ;          P(D)        -- type of things,         e.g. "person"
  Relation ;      D -> D -> T -- relation between things,e.g. "employed at"
  Property ;      D -> T      -- property of things,     e.g. "employed at Google"
  Individual ;    D           -- one entity,             e.g. "Google"
  Name ;          D           -- person, company...      e.g. "Eric Schmidt"


Characteristics:
- simple AST's, lots of variants (easily hundreds per query)
- semantic overgeneration, e.g. "Google works at Larry Page"
- some ambiguities, e.g.

    > give me the organizations and their locations
    MQuery (QFun Location (SAll Organization))
    MQuery (QFunPair (SAll Organization) Location)
   
  Maybe harmless?

Resource grammar was not quite enough; added for instance multiple interrogatives
("who is employed as what where") in Extra and ExtraEng

