  Determining the maximal separation between sensitivity and block sensitivity
of Boolean functions is of interest for computational complexity theory. We
construct a sequence of Boolean functions with bs(f) = 1/2 s(f)^2 + 1/2 s(f).
The best known separation previously was bs(f) = 1/2 s(f)^2 due to Rubinstein.
We also report results of computer search for functions with at most 12
variables.
