A flow graph 𝐹 with entry node (1) and exit node (11) is shown below: How…
2019
A flow graph 𝐹 with entry node (1) and exit node (11) is shown below:
How many predicate nodes are there and what are their names?
- A.
Three: (1,(2,3),6)
- B.
Three: (1,4,6)
- C.
Four: ((2,3),6,10,11)
- D.
Four: ((2,3), 6,9,10)
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Correct answer: A
Answer: There are three predicate (decision) nodes: 1, the node labeled 2,3, and 6.
Definition: A predicate (decision) node is any node where control can split to two or more different successors.
Node 1: Node 1 acts as a decision/entry point in the flow (it is part of the loop/entry control), so it serves as a predicate.
Node labeled "2,3": This node clearly branches to the left into node 6 and to the right into nodes 4/5, so it has multiple successors and is a predicate.
Node 6: Node 6 branches to nodes 7 and 8 (two different successor paths), making it a predicate node.
Note: Nodes such as 4, 5, 7, 8, 9, 10, and 11 are not predicate nodes because they do not split control (they have a single successor or are terminal).
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