| Summary: | Constructing catalogue of temporal situations
The paper is aiming to create a common basis for description, comparing, and analysis natural languages. As a subject of comparison we have chosen temporal structures of some languages. For such a choice there exists a perfect tool, describing basic temporal phenomena, namely an ordering of states and events in time, certainty and uncertainty, independency of histories of separate objects, necessity and possibility. This tool is supported by the Petri nets formalism, which seems to be well suited for expressing the above mentioned phenomena. Petri nets are built form three primitive notions: of states, of events that begin or end the states, and so-called flow relation indicating succession of states and events. This simple constituents give rise to many possibilities of representing temporal phenomena; it turns out that such representations are sufficient for many (clearly, not necessarily all) temporal situations appearing in natural languages.
In description formalisms used till now there is no possibility of expressing such reality phenomena as temporal dependencies in compound statement, or combination of temporality and modality. Moreover, using these formalisms one cannot distinguish between two different sources of uncertainty of the speaker while describing the reality: one, due to the lack of knowledge of the speaker what is going on in outside world, the second, due to objective impossibility of foreseen ways in which some conflict situations will be (or already have been) resolved. Petri net formalism seems to be perfectly suited for such differentiations.
There are two main description principles that encompassed this paper. First, that assigns meaning to names of grammatical structures in different languages may lead to misunderstanding. Two grammatical structures with apparently close names may describe different reality. Additionally, some grammatical terms used in one language may be absent and not understandable in the other. It leads to assign meanings to situations, rather than to linguistic forms used for their expression. The second principle is limit the discussed issues to such a piece of reality that can be possible for precise description. The third is to avoid introducing such information to the described reality that is not explicitly mentioned by linguistic means. The authors try to following these principles in the present paper.
The paper is organized as follows. First, some samples of situations related to present tense are given together with examples of their expressions in four languages: English, (as a reference language) and three Slavic languages, representing South slavonic languages (Bulgarian), West slavonic languages (Polish), and East slavonic languages (Russian). Within the same framework the next parts of the paper are constructed, supplying samples of using Past tenses and, finally, future tenses and modalities.
The formal tools for description purposes are introduced stepwise, according to needs caused be the described reality. There are mainly Petri nets, equipped additionally with inscriptions or labeling in order to keep proper assignations of description units to described objects.
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