  In the framework of the Gross-Pitaevskii mean field approach it is shown that
the supersonic flow of a Bose-Einstein condensate can support a new type of
pattern--an oblique dark soliton. The corresponding exact solution of the
Gross-Pitaevskii equation is obtained. It is demonstrated by numerical
simulations that oblique solitons can be generated by an obstacle inserted into
the flow.
