Problem 48. Prove that a language A is decidable if and only if it is finite or there is a computable function f : N ? {0,1}* such that range(f)-A and each f(n) comes strictly before f(n + 1) in the standard enumeration of (0,1) Problem 48. Prove that a language A is decidable if and only if it is finite or there is a computable function f : N ? {0,1}* such that range(f)-A and each f(n) comes strictly before f(n + 1) in the standard enumeration of (0,1)