Towards Formalisation of Aspect (abstract)
Verbal aspect is an obligatory grammatical category in Polish while the distinction is absent in Swedish, which involves difficulties in automatic translation from Swedish to Polish.
The category of verbal aspekt in Polish is central for expressing: sentence focus, temporal reference of the situation, temporal characteristics of the action. The two latter functions can be related in a comparatively straight-forward way to Swedish but the first one poses enormous difficulties, particularly for a rule based description.
A model for a semantic supplement to a syntactic description of relations between languages is proposed. Parsed representations of source and target languages are assumed to be given in the model. Nodes in the source graph can be marked with weights, which are provided for the category of target language absent in source language.
An analogy with G.Fant's source-filter model for phonetics can help explain the purpose with weights. They represent semantic signals and semantic filters. The signals flow from the bottom, i.e. from lexical items, up to the root in a tree representation of a sentence.The signals may get transformed on their way up- get amplified or weakened - dependent on the context. In this way the information relevant for the category is swiftly accumulated from the whole tree. A transfer function provides an interpretation of the computed value to the target category. The three semantic dimensions tested in the model for aspect are: temporal conclusiveness of an action, completeness of a situation and definiteness of a situation.
The transferfunction is defined as follows:
complete 0.0 - 0.5, concluded 0.0 - 0.5, specific 0.5 - 1.0 = ACTION_IN_FOCUS -> IMPERFECTIVE
complete 0.0 - 1.0, concluded 0.0 - 0.5, specific 0.0 - 0.5 = NOT_SPECIFIC -> IMPERFECTIVE
complete 0.5 - 1.0, concluded 0.5 - 1.0, specific 0.0 - 1.0 = SPECIFIC -> PERFECTIVE
complete 0.5 - 1.0, concluded 0.0 - 0.5, specific 0.5 - 1.0 = NOT_CONCLUSIVE -> IMPERFECTIVE
complete 0.0 - 0.5, concluded 0.5 - 1.0, specific 0.0 - 1.0 = CONCLUSIVE -> PERFECTIVE
It is an enormous task to create a supplement of this kind in a full scale; it means comparing every element of the source language in the light of the categories of the target language. But once the job has been done we can hope for a better understanding of the two languages and direct applications for translation and tutoring.