Consider the following statements:S1: The sequence of procedure calls corresponds to a preorder trav

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Question

Consider the following statements:S1: The sequence of procedure calls corresponds to a preorder traversal of the activation tree.S2: The sequence of procedure returns corresponds to a postorder traversal of the activation tree.Which one of the following options is correct?

Accepted Answer

Correct Answer: (D) S1 is true and S2 is trueConcept -- Activation Trees and Traversal Order in Compiler Design:An activation tree represents the nesting structure of procedure calls during program execution. Each node corresponds to one activation (call) of a procedure, and a node A is the parent of node B if A calls B during A's execution.S1 -- Preorder traversal corresponds to procedure calls (TRUE): In preorder traversal, we visit the current node before visiting its children. When a procedure P is called, its node is 'visited' (the call is recorded) before any of the procedures it calls (its children) are invoked. This is exactly the preorder pattern: P appears in the call sequence before its callees. Thus, the sequence of procedure calls follows a preorder traversal of the activation tree.S2 -- Postorder traversal corresponds to procedure returns (TRUE): In postorder traversal, we visit the current node after all its children have been visited. When a procedure returns, all procedures it called have already returned. The return of a procedure happens only after all its callees have returned. This is exactly the postorder pattern. Thus, the sequence of procedure returns follows a postorder traversal of the activation tree.Both statements are correct, making option D the answer. This is a classical result from Chapter 7 of the Dragon Book (Compilers: Principles, Techniques, and Tools by Aho, Lam, Sethi, and Ullman).

Consider the following statements:S1: The sequence of procedure calls corresponds to a preorder traversal of the activation tree.S2: The sequence of procedure returns corresponds to a postorder traversal of the activation tree.Which one of the following options is correct?

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Consider the following statements:S1: The sequence of procedure calls corresponds to a preorder traversal of the activation tree.S2: The sequence of procedure returns corresponds to a postorder traversal of the activation tree.Which one of the following options is correct?

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