2009-10-04 Transition systems cs http://www.google.co.jp/url?sa=t&source=web&ct=res&cd=2&url=http%3A%2F%2Fwww-i2.informatik.rwth-aachen.de%2FTeaching%2FCourse%2FPMC%2F2005%2Fpmc_lec1.pdf&ei=kbXISujQHYTq6gPl_dHwBA&usg=AFQjCNG1H8ss7A-Xogei2hgLSW6ctlaaKg&sig2=GvrtKwAJMrutnJTaKp6grQ