Before revision:  The baseline for ATSP here is a simple enumeration of cycle covers which can be done in time bounded by O^*(\mu(d)^n) for a function \mu(d)\le(d\rceil!)^{ n /{d\rceil}}.
After revision:  The baseline for ATSP here is a simple enumeration of cycle covers which can be done in time bounded by O^*(\mu(d)^n) for a function \mu(d)\le(d\rceil!)^{ 1 /{d\rceil}}.