  This paper proposes a distributed algorithm which deterministically gathers n
(n > 4) asynchronous, fat robots. The robots are assumed to be transparent and
they have full visibility. The robots are initially considered to be
stationary. A robot is visible in its motion. The robots do not store past
actions. They are anonymous and can not be distinguished by their appearances
and do not have common coordinate system or chirality. The robots do not
communicate through message passing. In the proposed gathering algorithm one
robot moves at a time towards its destination. The robot which moves, is
selected in such a way that, it will be the only robot eligible to move, until
it reaches its destination. In case of a tie, this paper proposes a leader
election algorithm which produces an ordering of the robots and the first robot
in the ordering becomes the leader. The ordering is unique in the sense that,
each robot, characterized by its location, agrees on the same ordering. We show
that if a set of robots can be ordered then they can gather deterministically.
The paper also characterizes the cases, where ordering is not possible. This
paper also presents an important fact that, if leader election is possible then
gathering pattern formation is possible even with no chirality.
