Final answer:
Non-terminals in computer science and programming languages can be nullable if they can produce an empty string or epsilon.
Step-by-step explanation:
When we talk about non-terminals in computer science and programming languages, we are referring to symbols that represent groups of terminals (which are the basic units of a language, like individual letters or digits). A non-terminal is nullable if it can produce an empty string or epsilon.
For example, in a context-free grammar, consider a non-terminal symbol A that can derive the empty string. In this case, A is nullable because it can be replaced by nothing and still be considered valid. On the other hand, if A can only produce non-empty strings, it is not nullable.