Systems of quadratic inequalities
Andrei Alexandrovich Agrachev, Antonio Lerario · 2012
We present a spectral sequence which efficiently computes Betti numbers of a closed semi-algebraic subset of RPn defined by a system of qua-dratic inequalities and the image of the homology homomorphism induced by the inclusion of this subset in RPn. We do not restrict ourselves to the term E2 of the spectral sequence and give a simple explicit formula for the differential d2.