Margarita V. Korovina Nicolai Vorobjov Satisfiability of Viability Constraints for Pfaffian Dynamics. 260-269 2006 conf/ershov/2006 Ershov Memorial Conference http://dx.doi.org/10.1007/978-3-540-70881-0_23 db/conf/ershov/ershov2006.html#KorovinaV06