Concurrency and Backtracking in Vienna Parallel Logic

            Eva Kühn and Herbert Pohlai and Franz Puntigam
    University of Technology Vienna, Institute of Computer Languages
           Argentinierstr. 8, A-1040 Vienna, Austria, Europe
                 {eva,franz}@mips.complang.tuwien.ac.at

VPL (Vienna Parallel Logic) supports the concurrent execution of
communicating processes and the computation of several alternative solutions
by means of programmed backtracking. It unifies the two worlds of Prolog and
concurrent logic programming languages like Parlog. Aspects of both language
classes can be combined to any desired degree within one computation. Our
proposal considers the treatment of failing processes. Further characteristics
include an advanced transaction model and the support of an object-oriented
and architecture-neutral programming style. VPL is a persistent language and
programming system. We describe the language and briefly outline
implementation issues of our prototype system. 

Keywords:
concurrent logic language, programmed backtracking, persistent transactions.