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What is the formula to compute the transitive closure of a graph?(a) tij(k) = tij(k-1) AND (tik(k-1) OR tkj(k-1))(b) tij(k) = tij(k-1) OR (tik(k-1) AND tkj(k-1))(c) tij(k) = tij(k-1) AND (tik(k-1) AND tkj(k-1))(d) tij(k) = tij(k-1) OR (tik(k-1) OR tkj(k-1))The question was posed to me in unit test.This intriguing question comes from Shortest Path topic in section Shortest Path of Data Structures & Algorithms II |
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Answer» CORRECT answer is (b) TIJ(k) = tij(k-1) OR (TIK(k-1) AND tkj(k-1)) Explanation: TRANSITIVE closure of a graph can be computed by using Floyd Warshall algorithm. This method involves substitution of logical operations (logical OR and logical AND) for arithmetic operations min and + in Floyd Warshall Algorithm. Floyd Warshall Algorithm: dij(k)=min(dij(k-1), dik(k-1) + dkj(k-1)) Transitive closure: tij(k)= tij(k-1) OR (tik(k-1) AND tkj(k-1)). |
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