Published online by Cambridge University Press: 22 January 2016
A measure μ(dx) on R is said to be unimodal with mode a if μ(dx) = cδa(dx) + f(x) dx, where c ≧ 0, δa(dx) is the delta measure at a and f(x) is non-decreasing for x < a and non-increasing for x > a. A measure is said to be unimodal with mode a if pn is non-decreasing for n ≦ a and non-increasing for n ≧ a. A probability measure μ(dx) on R (resp. on Z) is said to be strongly unimodal on R (resp. on Z) if, for every unimodal probability measure η(dx) on R (resp. on Z), the convolution μ*η(dx) is unimodal on R (resp. on Z).