  For a random variable we can define a variational relationship with practical
physical meaning as dI=dbar(x)-bar(dx), where I is called as uncertainty
measurement. With the help of a generalized definition of expectation,
bar(x)=sum_(i)g(p_i)x_i, and the expression of dI, we can find the concrete
forms of the maximizable entropies for any given probability distribution
function, where g(p_i) may have different forms for different statistics which
includes the extensive and nonextensive statistics.
