%0 Journal Article
%@ 1134-5632
%A Foschi, Rachele
%A Spizzichino, Fabio
%D 2008
%F eprints:705
%I 	Seccio de Matematiques i Informatica, E.T.S. d'Arquitectura, Universitat Politecnica
%J Mathware & Soft Computing
%N 1
%P 95-111
%T Semigroups of Semi-copulas and Evolution of Dependence at Increase of Age
%U http://eprints.imtlucca.it/705/
%V 15
%X We consider a pair of exchangeable lifetimes X, Y and the families of the conditional survival functions F t (x, y) of  (X − t, Y − t) given (X > t, Y > t). We analyze some properties of dependence and of ageing for F t (x, y) and  some relations among them