A question about Dijkstra's algorithm

From: Bilal Sallakh (afkar_at_mail2world.com)
Date: 01/18/04 

Date: 18 Jan 2004 09:30:58 -0800

Given a directed acyclic graph with all edges have negative weights.

Can we modify dijkstra's shortest path algorithm to find the shortest
path in such a

graph?

That is equivilant to:
Can we modify dijkstra's shortest path algorithm to find the longest
path in a direct

acyclic graph with all edges have positive weights?

I know that in both cases a linear algorithm suffices where we "relax"
the edges of

the vertices taken into topological order -The so called Bellman
Algorithm. But I'm

discussing Dijkstra's.

Also I expect that no modification can be found.

But our instructor insists that some modifications can make dijkstra's
algoirthm work.

He claims that he read that in an old reference.

Regards.