Further notes about CardWorld
2010 June 8, 9 - James A. Mason
Why CardWorld is not a
"toy" example
- Its pragmatic domain, though simple, feels quite "natural" to a
human user and can be extended in various directions. It is a
minimal but reasonably self-contained pragmatic domain. Playing
cards are all the same size, and although cards are almost
two-dimensional, they can cover one another, making for interesting
non-permanent collections. Most people already know about cards
and how to manipulate them. They know that cards are two-sided
flat objects that can be moved around, turned over, shuffled, and
stacked. The first version of CardWorld, CardWorld1, does not
even require knowledge about playing cards, because it only deals with
cards as simulated physical objects.
- Because the pragmatic domain is reasonably simple, it can be
modeled thoroughly, with few additional simplifying assumptions.
That
permits the focus of the CardWorld project to be on modeling the
syntax, semantics, and pragmatics of English-language interactions with
it or, more accurately, with a simulated card agent
playing the role of a person. Yet the pragmatic domain is rich
enough to support many aspects of English syntax and semantics,
including many extensions beyond the aspects modeled in CardWorld1.
What CardWorld1 illustrates about natural-language understanding
- Understanding a natural language is not an all-or-nothing
ability. In the beginning it does not require recursively nested
syntax, the ability to perform deductive logic, and other abilities
that are required for the full fluency of a well-educated adult.
We know that, of course, from the language abilities of children.
In most cases the CardAgent component of CardWorld1 understands the
utterances that it accepts as well as, and in the same way as, a person
would. To the extent that its understanding differs from that of
most persons, it simply needs correction and refinement.
- The only requirements for communication by means of a language
are: (1) a shared pragmatic environment, (2) an ability to exchange
utterance tokens, (3) vocabulary, parsing and interpretation abilities
which have
enough in common between the interlocutors that the intended pragmatic
effects of utterance actions can be accomplished. CardWorld1
meets all those requirements.
- CardWorld1 illustrates some specific subtleties about
direct-definite, deictic and anaphoric reference in English:
- The type of thing referred to, as well as the instance referred
to, can be anaphoric. e.g. "Turn over this pile." "Now
turn over that one." ("one" refers to "pile")
- Singular separate reference can be anaphoric. e.g. "Turn
over each pile." "Then shuffle it and spread it out." ("it"
refers to each pile separately.)
- Definite reference with the unique quantifier "the" can refer
to the only instance, among a set of instances, to which the action
specified by the verb can be applied. e.g. "shuffle the pile"
when there is one multi-card pile and one or more separate singleton
cards. (A pile consisting of a single card can't be shuffled.)
- Definite reference with the unique quantifier "the" can refer
to the unique non-degenerate instance among a set of instances, all but
one of which are degenerate. e.g. "turn over the pile" when there
is a multi-card pile as well as some singleton cards. (This
differs from example 3, because singleton cards can be turned over.)
- Definite reference with the unique quantifier "the" can refer
to an instance which is separate from one or more
collections of two or more instances of the same type. e.g. "turn
over the
card" when there is one card alone by itself while the other cards are
in multi-card piles.
- Reference with the unique quantifier "the" can be deictic if it
would otherwise be ambiguous except that there is an instance of the
type which has recently been singled out. e.g. move a card, then
"turn over the card".
CardWorld
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