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Sunday, November 2, 2025

2025-287

Considering the Traveling Salesman Problem (TSP) in a complete graph where the triangular inequality holds, which of the following statements most accurately describes the fundamental difference in tour construction and performance guarantee between the Rosenkrantz-Stearns-Lewis algorithm and the Christofides algorithm?

  1. Both algorithms are based on the "Farthest Insertion" heuristic, but Christofides applies additional optimization using dynamic programming to achieve a 1.5 x optimal cost guarantee, while Rosenkrantz-Stearns-Lewis does not.

  2. Christofides' algorithm uses minimum perfect matching over the odd degree nodes of the minimum spanning tree (MST) to construct an Eulerian graph, achieving an approximation guarantee of 1.5 x optimal cost. In contrast, the Rosenkrantz-Stearns-Lewis algorithm duplicates all edges of the MST, resulting in a guarantee of 2 x optimal cost.

  3. The Rosenkrantz-Stearns-Lewis algorithm duplicates the edges of the MST to form an Eulerian tour, and the Christofides algorithm improves on this by finding a minimum perfect match on all nodes in the graph (not just those of odd degree), but both algorithms share the same 2 x cost-optimal performance guarantee.

  4. The Rosenkrantz-Stearns-Lewis algorithm uses a minimum perfect match over the odd degree nodes of the MST, achieving a 1.5 x optimal cost guarantee, while the Christofides algorithm duplicates all MST edges, achieving a 2 x optimal cost guarantee.

  5. None of the above.


Original idea by: Juan Jose Rodriguez Rodriguez

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