A special class of scheduling problems is studied in this paper,
named Hybrid Flowshop, n jobs have to be performed
in a shop and each of them has the same routing (so this is
a flowshop). A job consists in k different operations.
A set of machines are able to perform each operation and this
set is called a stage. So when a job consists in two operations,
there are two stages in the shop. After introducing the scheduling
generalities, we define our preocupations and we propose a notation
in order to identify precisely and rapidly a problem. Then a state
of the art is proposed and presented in two parts. The first one is
dedicated to the 2-stage hybrid flowshops and the second to the
general case of the k-stage. Then a summary puts to the fore
that many problems remain unsolved.