Elizaveta A. Okol'nishnikova On Operations of Geometrical Projection and Monotone Extension Electronic Colloquium on Computational Complexity (ECCC) 2000 7 6 db/journals/eccc/eccc7.html#ECCC-TR00-006 http://eccc.hpi-web.de/eccc-reports/2000/TR00-006/index.html