Consider the sentence “AlexMennen does not believe this sentence”. If you believe it, you’re wrong. If you don’t, you’re wrong.
I think the sentence “AlexMennen will be hanged tomorrow but will believe he won’t be hanged” is similar. If you tomorrow believe it, you believe a contradiction and therefore you’re wrong. If tomorrow you don’t believe it, you get hanged and proven wrong.
Consider the sentence “AlexMennen does not believe this sentence”. If you believe it, you’re wrong. If you don’t, you’re wrong.
I think the sentence “AlexMennen will be hanged tomorrow but will believe he won’t be hanged” is similar. If you tomorrow believe it, you believe a contradiction and therefore you’re wrong. If tomorrow you don’t believe it, you get hanged and proven wrong.