GPU-accelerated tree-based exact optimization methods 173
of subproblems such that the resolution of L lasts T minutes with a sequential
B&B. So by initializing the pool of our sequential B&B with the subproblems
of this list L, we are sure that the resolution of the sequential B&B will last
T cpu minutes such as T cpu will be approximately equal to T . Therefore, it
will be possible to initialize the pool of our GPU B&B with the same list
L of subproblems in order to compute the speedup. Let us suppose that the
resolution of the GPU B&B will last T gpu minutes. So the speedup of our
GPU algorithm will be equal to T cpu/T gpu. With this experimental protocol,
the subproblems explored by the GPU and CPU B&B versions will be exactly
the same. So to