[MUD-Dev] English grammar thoughts

Robert Zubek rob at cs.northwestern.edu
Tue Oct 23 01:07:30 New Zealand Daylight Time 2001

Par Winzell:

> So, first, what I think I know: in English, the direct object is
> the answer to the question 'What did you put? wave? fill? nod?' 
> and thus invariant under word-order juggling -- in

>   'wave my sword at the sky'

> and

>   'wave at the sky with my sword'

this question is easier to answer in latin or slavic languages,
where the direct object can be detected from the accusative case on
the noun. in english, which collapses almost all of the cases, the
distinctions aren't as clear-cut and the question gets more tricky
to answer.

basically, sentence parts (subject, objects, etc.) are not the same
as semantic roles (agent, patient, etc.), and are very much
contingent or word order, at least in english. taking passive-voice
transformation as an example:

  1a. the burger was flipped by the cook
      subject - passive verb - (indirect object?)
  1b. the cook flipped the burger
      subject - verb - object

in 1a, the burger is the subject of the passive form of the verb - a
prepositional phrase specifies the agent, but he nevertheless does
not become the subject. in 1b, on the other hand, the subject is the
cook, and the direct object is the burger. and yet, even though the
syntactic structure is drastically different, the semantics of the
phrase, the answer to the question "who flipped the burger", remains
the same.

because parts of sentence don't convey the semantics of language
very clearly, they get somewhat unwieldy to use in practice. what
one might use instead are explicit semantic representations - that
is, each verb creating a frame with semantic roles that need to be
filled in, such as agent (the performing party), patient (the
recipient of the action), instrument (a tool used in the action),
and so on, with the particulars depending on the verb.  in this way,
one could translate the above sentences into following semantic

  2a. flip (+past +passive): agent = cook, patient = burger
  2b. flip (+past): agent = cook, patient = burger

this representation makes it much clearer that 1a and 1b represent
the same kind of an action.

alas, in case of naturally occuring utterances, extracting semantic
roles from surface form is usually a pain involving creating a
myriad of rules. in your case, however, since you can restrict the
grammar any way you want, perhaps the rule set could be made small
enough that it woldn't be that big of a problem...?

but it could be that the whole thing's an overkill, i don't know. ;)

> Next, I believe the following configuration parameters would
> specify a verb's expressive possibilities completely:

>   Evoke:               Forbid/Allow/Require
>   Direct Object:       Forbid/Allow/Require
>   Direct Preposition:  Forbid/Allow/Require
>   Indirect Object:     Forbid/Allow/Require

>     [ I think there's always a preposition before the direct
>     object ]

>   List of Direct Object Prepositions:    [list]
>   List of Indirect Object Prepositions:  [list]

afaik, direct objects never have prepositions - and for indirect
objects, a really cool table of common prepositions, along with
frequency of usage in english, can be found in jurafsky and martin,
_speech and language processing_, p. 292.

sorry, i'm not sure i follow the first rule - what do you mean by

> Finally, does anybody know what the relationship is between the
> notions of on one hand direct and indirect objects and the object
> of the preposition, and on the other hand noun cases like
> nominative, accusative, dative, etc?

it's messy - i tried doing it for english once, but wasn't very
satisfied with the results, because english collapses virtually all
of the different declinations into similar forms. my
back-of-the-envelope sketch is as follows:

  nominative: subject or complement of verb
    I go, WE go, etc.
    pronouns: i/you/he/she/it/we/you/they
  genitive: "of" forms, possessive (and partitive?)
    i met JOHN'S family, i met the family OF JANE, i met HIS family, etc.
    pronouns: my/your/his/her/its/our/your/their/X's
  dative: "to", "for" forms, indirect object
    give it to HIM, i gave JANE the pen, etc.
    pronouns: me/you/him/her/it/us/you/them
  accusative: direct object
    i gave john THE PEN, cook flipped THE BURGER, etc.
    pronouns: i/you/he/she/it/we/you/they
  ablative: "with" forms
    he went with JANE, she read with CARE
  locative: "at", "in" forms, often colocative
    he is at THE STORE, she is in THE ROOM

this is only a sketch from memory - any textbook on latin or slavic
languages would give you better info on this. to return to your
example, in a more declined language, in the phrase "wave at the sky
with my sword", sword would be ablative, and not an objects direct
or indirect.

still, cases are cool. if english only used properly declined nouns,
parsing would be so much easier! :)

hope this helps,


Robert Zubek
rob at cs.northwestern.edu

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