casa333 just a few points.
A tarif is not an end point for the sentence , it is just the minimum time that must be served before an application for parole can be started. The actual release date ( even if granted) will be some time (normally several years) after that.
The sentence reduction for an early guilty plea is 1/3rd not 1/2 .
Automatic release at the 1/2 way point is ONLY for sentences of less than 4 years.
Lastly life does mean life, in that if a 'lifer' is released after say 25 years they are still sentenced to 'life'so if they do commit another crime or are even arrested they can be sent straight back to jail without another trial. There are cases where someone has served many years of a life sentence then been free on licence for years but was then sent back to jail . I rememer a case where a 'lifer' served 20 years was free for another 20 years only to be returned to jail in his 70s fora minor theft. The release does NOT 'cancel' the life sentence which remains in force until the offender dies.
A