摘要
Ⅰ. MAIN RESULT Let (Ω,P) be a probability space, and H a nonempty family of random variables. We denote by ess. inf H or ess. inf ξ∈ H the essential infimum of H, which always exists. In this note we only deal with the ess. inf case, the transplantation of results to the ess. sup case being trivial.
