The 
-Bass
conjecture asserts that the Hattori-Stallings
trace of every idempotent matrix over the
complex discrete group algebra of a discrete
group has finite support on conjugacy
classes of finite-order
elements. For 
, write 
for the sum of its diagonal coefficients over 
. The conjectured conclusion is that a finite
set 
of such classes satisfies
 |
for every 
. This is stronger than just vanishing on classes
of elements of infinite order.
Absolute summability of the trace coefficients does not alone imply finite
support.
