 
Summary: A STABLE TRACE FORMULA II. GLOBAL DESCENT
James Arthur*
Contents
Introduction
§1 Statement of a theorem
§2 Extensions and ramifications
§3 The mapping X (G) Y(G)
§4 Descent and global transfer factors
§5 Transfer factors for Gc
§6 Proof of the theorem
* Supported in part by NSERC Operating Grant A3483.
1
Introduction
This paper is the second of three articles designed to stabilize the trace formula. The
goal is to stabilize the global trace formula for a general connected group, subject to a
condition on the fundamental lemma that has been established in some special cases. In
the first article [I], we laid out the foundations of the process. We also stated a series of
local and global theorems, which together amount to a stabilization of each of the terms in
the trace formula. In this paper, we shall take a significant step towards the proof of the
theorems. We shall reduce the proof of Global Theorem 1 of [I, §7] to the special case of
