How to know if someone has achieved nirvana? A monk in Sri Lanka publicly says that he has achieved nirvana.If that's true we can follow the (practical) path he teaches . But how can we make sure whether that is true or not ?
You'll only know other's achievement of nirvana if and only if you've achieved nirvana yourself. It is the same as real life, if you've not reached the same level as your opponent in the same field, you'll never tell if your opponent is of the same level as you.