I'm currently learning some things about BSS RAMs.
For sake of simplicity, please imagine them as a Turing machine over the reals.
Now, this machine gets some real numbers as input. The input values form nearly a string, but are not of finite length as decimal representation. Additionally, there are infinitely many real numbers.
A language on the other hand is often defined as being a subset of Kleene's Hull over a finite (!) alphabet.
Is it valid and reasonable to define languages over an infinite alphabet to represent the input set of a BSS RAM?