Dimitrova, N.; Markov, S. M.; Popova, E. D.: **Extended
Interval Arithmetics: New Results and
Applications** *Computer Arithmetic
and Enclosure Methods*. Atanassova, L.; Herzberger, J. (Eds.)
Elsevier Sci. Publishers B. V., 1992, pp. 225-232.

In this paper we compare two well studied interval arithmetic structures, which are different extensions of familiar interval arithmetic; the first one is obtained by extending the concept of interval, the other by extending the set of basic arithmetic operations. Certain relations between these two structures have been formulated which outline a new direction of applications. By demonstrating that all theorems of both theories have analogues in each other we conclude that both structures can be equally well used in practical applications.