next up previous
Next: Conclusions Up: Exploitation of Valency List Previous: Semantic Classification of Verbs


Determining TIL Construction Representing the Verb Meaning

TIL, or Transparent Intensional Logic (see [8,9,10]), is a logical system, suitable for representing meaning of a natural language expression. The system is a typed lambda-calculus logic with hierarchy of types. It is a parallel to Montague's logic, however TIL has the power of greater expressivity while retaining the simplicity of the basic idea. Moreover, the inference rules for TIL are well defined, thus enabling us to use constructions as an instrument for representing sentence meaning in a knowledge base system.

If we want to translate a sentence into a TIL construction, we first need to know the constructions that correspond to particular words in the sentence together with their types. Among them the construction representing a verb usually forms the basic part of the resulting construction and constructions of other words form its arguments. To determine the verb construction seems to be more difficult than it is perhaps with a noun.

The semantic classification of verbs from the previous paragraph divides verbs into groups, that share the same type of construction. Moreover, it is possible to formulate rules for deducing the type directly from the valency list for a verb.

We derive the type from the valency list of a class in the following way -- first we construct a set of all valency expressions that appear in the valency list for a verb, so called multi-valency. The multi-valency is a schema of all possible expressions that can be tied with the verb, the verb ``arguments''. It also shows the number and kind of each argument. We assume that the verb expresses a relation between (at most) these arguments. In the sentence where some of these expressions are not present, the corresponding arguments are filled with null values. This approach allows to fill in a value of an argument that is missing in the sentence but is known from the preceding text and thus it semantically belongs to the verb.

The expressions can be translated to verb arguments in the following ways:

  1. hQ (quality) is regarded as properties of individuals, -objects.

  2. hM (amount) expresses a number of some individuals, it is an extensional (not dependent on the actual world or time) relation between a number and an individual or individuals, a -object (logical object of type ).

  3. hP (person) and hT (thing) can express an individual role or a class of individuals, thus it has type or . Only during the analysis of a particular sentence it can be determined which one of these types should be used and in some cases it cannot be determined at all since the respective expression can be ambiguous.

  4. hA (where to), hF (where from), hD (which way) and hR (reflexive pronoun) usually serve as modificators of the verb meaning. Therefore they do not change the type of the verb construction, they are functions that show the logical object expressing the modified meaning of a verb.

  5. all sX expressions refer to another construction, thus they are of a higher rank type .


next up previous
Next: Conclusions Up: Exploitation of Valency List Previous: Semantic Classification of Verbs
Pavel Smrz 2001-03-18