Suppose the adjacency relation of vertices in a graph is represented in a table Adj(X,Y). Which of the following queries cannot be expressed by a relational algebra expression of constant length?
A
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List of all vertices adjacent to a given vertex
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B
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List all vertices which have self loops
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C
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List all vertices which belong to cycles of less than three vertices
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D |
List all vertices reachable from a given vertex
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