CONJUGACY CLASSES OF MAXIMAL TORI IN SIMPLE REAL ALGEBRAIC-GROUPS ANDAPPLICATIONS

Let G be an almost simple complex algebraic group defined over R, and let G(R) be the group of real points of G. We enumerate the G(R)-conju gacy classes of maximal R-tori of G. Each of these conjugacy classes i s also a single G(R)-degree-conjugacy class, where G(R)-degree is the identity component of G(R), viewed as a real Lie group. As a consequen ce we also obtain a new and short proof of the Kostant-Sugiura's theor em on conjugacy classes of Cartan subalgebras in simple real Lie algeb ras. A connected real Lie group P is said to be weakly exponential (w. e.) if the image of its exponential map is dense in P. This concept wa s introduced in [HM] where also the question of identifying all w.e. a lmost simple real Lie groups was raised. By using a theorem of A. Bore l and our classification of maximal R-tori we answer the above questio n when P is of the form G(R)-degree.