The lexical analysis for a modern computer language such as Java needs the power of which one of the following machine models in a necessary and sufficient sense?
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Answer: A
The correct option is A.
Explanation:
- Role of Lexical Analysis: The primary task of a lexical analyzer (scanner) is to read the input characters of the source program, group them into lexemes, and produce a sequence of tokens (such as keywords, identifiers, operators, and constants).
- Language Class: These tokens are specified using regular expressions. The set of all valid tokens forms a regular language.
- Machine Model: The class of automata that is both necessary and sufficient to recognize regular languages is the Finite State Automaton (FSA) (either deterministic or non-deterministic, as they are equivalent in power).
Why other options are incorrect:
- Deterministic / Non-deterministic Pushdown Automata (DPDA / NPDA): These are used for recognizing context-free languages (like syntax analysis/parsing). While they have the power to recognize regular languages, they are not necessary because a simpler model (FSA) is sufficient.
- Turing Machine: This is used for recursively enumerable languages and is far too powerful and computationally expensive for lexical analysis.
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