Onsha <- function(a,b,c,p,q) {
p*((1/a)/(1/a+1/b+1/c))/ ( p*((1/a)/(1/a+1/b+1/c)) + q*((1/b)/(1/a+1/b+1/c)) + (1-q)*((1/c)/(1/a+1/b+1/c)) )
}
> Onsha(10,10,10,0.5,0)
[1] 0.3333333
> Onsha(10,10,10,0.5,0.3)
[1] 0.3333333
> Onsha(10,20,30,0.5,0.3)
[1] 0.5660377

恩赦確率が同じときは、看守の嘘つき確率の影響は受けないね。