发现CS里面有各种各样的Y-Chart，顾名思义就是长得像Y的图。这里总结一下，只为好玩。
Model Checking 可爱版
参考链接： Model Check可爱版来自：A Specification Patterns System for Discrete Event Systems Analysis http://www.intechopen.com/journals/international_journal_of_advanced_robotic_systems/a-specification-patterns-system-for-discrete-event-systems-analysis