Question

Which one of the following is TRUE at any valid state in shift-reduce parsing?
1. Viable prefixes appear only at the bottom of the stack and not inside
2. Viable prefixes appear only at the top of the stack and not inside
3. The stack contains only a set of viable prefixes
4. The stack never contains viable prefixes

Answer 1

Correct Answer - Option 3 : The stack contains only a set of viable prefixes

Viable Prefixes: The set of prefixes of right sentertict forms that can appear on the stack are called viable prefixes.

The stack contains only a set of viable prefixes at a given time.