Akbulut
corks
and
non-trivial
involutions
on
instanton
Floer
homology”
We
consider
a
certain
family
of
compact
and
contractible
4-manifolds,
called
corks,
recently
constructed
by
Akbulut
and
Yasui.
Each
cork
Wn
gives
rise
to
exotic
structures
on
smooth
4-manifolds
via
an
involution
of
their
boundary
integral
homology
3-sphere.
The
cork
W1,
also
known
as
Akbulut’s
cork,
and
its
boundary
involution
was
the
first
example
of
a
diffeomorphism
acting
non-trivially
on
the
instanton
Floer
homology
of
an
irreducible
homology
3-sphere.
In
this
talk,
we
will
show
that
each
cork
Wn
has
a
diffeomorphism
on
the
boundary
that
acts
non-trivially
on
the
Floer
homology.