Abstract
For
SU(2)
(or
SO(3)
) Donaldson theory on a 4-manifold
X
, we construct a simple geometric representative for
μ
of a point. Let
p
be a generic point in
X
. Then the set
{[A]|
F
−
A
(p)
is reducible
}
, with coefficient -1/4 and appropriate orientation, is our desired geometric representative.