A mathematical paper can state in one section that P is a prime number at least five and later refer to P without repeating that condition.

“But in practice, this is not, uh, this is not what happens. In practice, you, you read, you read section three of the paper. In section three it says, "From this point, P will be a prime number which is at least five."”

“And then you read something in section seven of the paper and it's just talking about a number called P and you know from reading lots of number theory papers that P will be a prime number.”