Gov. Beverly Perdue said late yesterday that she has no plans to release 20 prison inmates next week, despite a recent state Supreme Court ruling that they had served out their life sentences and should be freed. The Supreme Court ruled two weeks ago that a state law from 1970s defined a life sentence as 80 years and that, when good-behavior credits were included, some inmates had completed their sentence. The law was changed a few years later. Under the ruling, the inmates are set to be released next Thursday.