The decomposition of a constructible set into a union of
quasi-algebraic sets is often a first step to solve many problems and
it is sometimes desirable to have as few cases to consider as
possible. We derive decision criteria and algorithms for testing
inclusion and equality relations between two unions of quasi-algebraic
sets and between rational functions defined on them. We emphasize
flexibility in practical representations of these geometry objects and
in implementation of the criteria. The algorithms are implemented in
Axiom and used to refine Sit's algorithm for parametric linear
systems. Our main result can be applied to obtain an irredundant
decomposition of a constructible set.
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