=ADD= =reftype= 14 =number= 00-23 =url= ftp://ftp.risc.uni-linz.ac.at/pub/techreports/2000/00-23.ps.gz =year= 2000 =month= 06 =author= Ratschan; Stefan =title= Convergence of Approximate Constraint Solving by Approximate Quantifiers =abstract= In this paper we are interested in solving quantified real constraints (i.e., first-order formulas over the real numbers). When trying to solve such constraints exactly, one faces the following problems: First, constants coming from measurements are often only approximately given. Second, solving such constraints is in general undecidable and for special cases highly complex. Third, exact solutions are often extremely complicated symbolic expressions. Thus we do approximate computation instead --- working on approximate inputs and producing approximate output. One of the oldest approaches for dealing with such uncertainty is set theory. It has been used for this purpose from its beginnings in laying the foundations of mathematics, to many modern practical applications, for example in the area of interval mathematics. We show that set theory can be applied in a similar way to solving quantified constraint approximately. For this we use the notion of heterogenous power algebra, which results in a general framework for approximate computation that can be applied in various different domains. =sponsor= FWF SFB1303