@article {2012,
title = {Systems of Quadratic Inequalities},
journal = {Proceedings of the London Mathematical Society, Volume 105, Issue 3, September 2012, Pages 622-660},
number = {arXiv:1012.5731;},
year = {2012},
publisher = {SISSA},
abstract = {We present a spectral sequence which efficiently computes Betti numbers of a
closed semi-algebraic subset of RP^n defined by a system of quadratic
inequalities and the image of the homology homomorphism induced by the
inclusion of this subset in RP^n. We do not restrict ourselves to the term E_2
of the spectral sequence and give a simple explicit formula for the
differential d_2.},
doi = {DOI: 10.1112/plms/pds010},
url = {http://hdl.handle.net/1963/7072},
author = {Andrei A. Agrachev and Antonio Lerario}
}