why negative edges cycles are allowed in bellman ford algorithms while no negative edge allowed in dijkstra algorithms?
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You want to know why his algorithm can deal with negative edges while Dijkstra's can't? – Bruno Brant Nov 29 '10 at 18:53
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Allowed? Bellman-Ford algorithm allows distinct edges with negative weights (not supported in Dijkstra algorithm), but neither algorithm "allows" negative cycles. The shortest path problem makes no sense in presence of a negative cycle, so there's no meaningful way to "allow" negative cycles in any such algorithm.
Bellman-Ford algorithm can be made to detect the presence of a negative cycle and abort execution (abort, since no correct solution exists in that case).
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