\newcommand{\etalchar}[1]{$^{#1}$}
\begin{thebibliography}{BOKR86}

\bibitem{Arnon_Collins_McCallum:84a}
D.~S. Arnon, G.~E. Collins, and S.~McCallum.
\newblock Cylindrical algebraic decomposition {I}: The basic algorithm.
\newblock {\em SIAM J. on Computing}, 13(4):865--877, 1984.

\bibitem{Arnon_Collins_McCallum:84b}
D.~S. Arnon, G.~E. Collins, and S.~McCallum.
\newblock Cylindrical algebraic decomposition {II}: An adjacency algorithm for
  the plane.
\newblock {\em SIAM J. on Computing}, 13(4):878--889, 1984.

\bibitem{Arnon_Collins_McCallum:88}
D.~S. Arnon, G.~E. Collins, and S.~McCallum.
\newblock An adjacency algorithm for cylindrical algebraic decompositions
  of three-dimensional space.
\newblock {\em J. Symbolic Comp.}, 5(1,2):163--187, 1988.

\bibitem{Arnon:81}
D.~S. Arnon.
\newblock {\em Algorithms for the Geometry of Semi-Algebraic Sets}.
\newblock PhD thesis, Comp. Sci. Dept., Univ. of Wisconsin-Madison, 1981.
\newblock Tech. Report No. 436.

\bibitem{Collins_Hong:91}
G.~E. Collins and H.~Hong.
\newblock Quantifier elimination by partial {CAD} construction.
\newblock {\em J. Symbolic Comp.}, 12(3):299--328, Sept. 1991.

\bibitem{Collins_McCallum:95}
G.~E. Collins and S. McCallum.
\newblock Adjacency algorithms for cylindrical algebraic decompositions
          of four and higher dimensional spaces.
\newblock In preparation.

\bibitem{Collins:75}
G.~E. Collins.
\newblock Quantifier elimination for the elementary theory of real closed
  fields by cylindrical algebraic decomposition.
\newblock In H.~Brakhage, editor, {\em Automata Theory and Formal Languages},
  volume~33 of {\em Lec. Notes Comp. Sci.}, pages 134--183. Springer-Verlag,
  Berlin, 1975.

\bibitem{Collins:95}
G.~E. Collins.
\newblock Quantifier elimination by cylindrical algebraic decomposition -
   twenty years of progress.
\newblock To appear.

\bibitem{Davenport:86}
J.~H. Davenport.
\newblock On a ``piano movers'' problem.
\newblock {\em ACM SIGSAM Bulletin}, 20 (1,2):15--17, 1986.

\bibitem{Dugundji:66}
J. Dugundji.
\newblock {\em Topology}.
\newblock Allyn and Bacon, Boston, 1966.

\bibitem{Hong:90}
H. Hong.
\newblock {\em Improvements in CAD-Based Quantifier Elimination}.
\newblock PhD thesis, Ohio State University, 1990.
\newblock Tech. Report No. OSU-CISRC-10/90-TR29.

\bibitem{Kalkbrener_Stifter:87}
M. Kalkbrener and S. Stifter.
\newblock Some examples for using quantifier elimination for the
   collision problem.
\newblock Technical Report 87-22, Research Institute for
   Symbolic Computation, J. Kepler University, Linz, Austria, 1987.

\bibitem{Schwartz_Sharir:83a}
J.~T. Schwartz and M. Sharir.
\newblock On the ``piano movers'' problem I.
   The case of a two-dimensional rigid polygonal body moving
   amidst polygonal barriers.
\newblock {\em Comm. on Pure and Applied Math.}, 26:345--398, 1983.

\bibitem{Schwartz_Sharir:83b}
J.~T. Schwartz and M. Sharir.
\newblock On the ``piano movers'' problem II.
   General techniques for computing topological properties
   of real algebraic manifolds.
\newblock {\em Advances in Applied Mathematics}, 4:298--351, 1983.
\end{thebibliography}
