The purpose of this talk is to present some stochastic ordering results among the lifetimes of two coherent systems consisting of two different sets of i.i.d. component lifetimes with the same signature vector in the sense of the hazard rate order, the reversed hazard rate order and the likelihood ratio order. Next, these comparisons results are combined into the known results in the literature to get more general results, in which the two systems have two different sets of component lifetimes as well as two different signature vectors.
