Parameters in Banach spaces and orthogonality

In Banach spaces, plenty of parameters have been considered: they are often dened by using pairs of vectors. Rarely they are dened by considering pairs of vectors which are orthogonal in the sense of Birkho and James; in that case the study is often not easy. In fact, it can be dicult to identify pairs of orthogonal vectors; so to calculate the value of these parameters, to compare them with the other parameters, to see if they have some stability with respect to changes of the norm. In this paper we shall do this for a couple of new parameters. Keywords: Orthogonal