7International Electro-Technical Commission (IEC). International Standard 61131-3 : Programmable Logic Controllers, Part 3 : Languages [S]. 1993.
8Mohrenschildt M. Symbolic verification of hybrid systems: An algebraic approach [J]. European Journal of Control, 2001, 7(5) : 541 - 556.
9Henzinger T A, Kopke P W, Puri A, et al. What's decidable about hybrid automata?[C]// Proc 27th Symposium on the Theory of Computing. Las Vegas, NV, USA, 1995.
10Woodcock J, Larsen P G, Bicarregui J, et al. Formal methods: Practice and experience [J]. ACM Computing Surveys, 2009, 41 (4): 1-36.
