GATE CS 2017 Set 2 Q6 — Parsing (LL, LR)

The "power" of a parser refers to the class of grammars it can successfully parse without any conflicts (shift-reduce or reduce-reduce).

The hierarchy of bottom-up parsers in terms of their parsing power is as follows:

• Statement I: "Canonical LR is more powerful than SLR" is CORRECT because any grammar that is $\text{SLR}(1)$ is also $\text{LR}(1)$, but the reverse is not always true.
• Statement II: "SLR is more powerful than LALR" is INCORRECT because $\text{LALR}(1)$ is strictly more powerful than $\text{SLR}(1)$.
• Statement III: "SLR is more powerful than Canonical LR" is INCORRECT because Canonical LR is the most powerful LR parser.

Thus, only statement I is correct.