Hauptvortrag: Quantifier elimination for real closed fields by cylindrical algebraic decomposition
Proceedings of the 2nd GI Conference on Automata Theory and Formal Languages
Polynomial-time computing over quadratic maps i: sampling in real algebraic sets
Computational Complexity
Algorithms in Real Algebraic Geometry (Algorithms and Computation in Mathematics)
Algorithms in Real Algebraic Geometry (Algorithms and Computation in Mathematics)
Computing the betti numbers of arrangements in practice
CASC'05 Proceedings of the 8th international conference on Computer Algebra in Scientific Computing
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For any fixed l 0, we present an algorithm which takes as input a semi-algebraic set, S, defined by P1 ≥ 0,...,Ps ≥ 0, where each Pi ∈ R[X1,...,Xk] has degree ≤ 2, and computes the top l Betti numbers of S, bk-1(S), ..., bk-l(S), in polynomial time. The complexity of the algorithm, stated more precisely, is Σi=0l+2 (si k2O((l,s)). For fixed l, the complexity of the algorithm can be expressed as sl+2 k2O(l), which is polynomial in the input parameters s and k. To our knowledge this is the first polynomial time algorithm for computing non-trivial topological invariants of semi-algebraic sets in Rk defined by polynomial inequalities, where the number of inequalities is not fixed and the polynomials are allowed to have degree greater than one. For fixed s, we obtain by letting l = k, an algorithm for computing all the Betti numbers of S whose complexity is k2O(s)