I am practicing for an exam and one of the exercises is:

Find an example sequence where FFD (offline) performs better than BFD (offline).

Intuitively I would say no such sequence exists as the sequence is sorted, but I have not managed to find a counterexample or proof.

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    $\begingroup$ FFD? BFD? More context would probably be helpful. $\endgroup$ – David Richerby Jan 17 '17 at 17:44

Isn't First/Best Fit Decreasing always considered offline (requiring sorting the input assumed unsorted)?
Anyway, let me assume "performs better" to mean uses less bins.
I find it annoyingly hard to try to find an example using a minimum number of items, of item values and minimum item values - and to argue convincingly that it is minimal, but

try a bin size of 16 and items of 11, 6, 6, 3, 2, 2, 2. Bin contents after adding each item:
- FF: 11 11,6 11,12 14,12 16,12 16,14 16,16
- BF: 11 11,6 11,12 11,15 13,15 15,15 15,15,2

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