Re: [Haskell-cafe] Performance of functional priority queues

Sebastian Sylvan wrote:

On Mon, Jun 15, 2009 at 4:18 AM, Richard O'Keefe wrote:

...

There's a current thread in the Erlang mailing list about priority queues. I'm aware of, for example, the Brodal/Okasaki paper and the David King paper. I'm also aware of James Cook's priority queue package in Hackage, have my own copy of Okasaki's book, and have just spent an hour searching the web.

One of the correspondents in that thread claims that it is provably impossible to have an efficient priority queue implementation

A priority queue based on skewed binomial heaps is asymptotically optimal (O(1) for everything except deleteMin which is O(log n)), so if that's what he means by "efficient" then he's most definitely wrong.

What about decreaseKey in a purely functional setting? I suppose it's O(log n), based on the intuition of trees with limited branching factor. Fibonacci heaps can do it in O(1), which makes a difference for Dijkstra's algorithm, for example. regards, Bertram