WHATEVER IS SPREADING.
(WAVES, IDEAS, NEWS, SOUND ETC.).

AND YOU?

WHAT WILL
YOU
PROPAGATE
TODAY ?

 ON A MANIFOLD X, THERE IS PROPAGATION AT THE POINT X0 IN THE CODIRECTION  ξ0  IF ONE CAN CROSS THE BOUNDARY AT X0 IN THIS CODIRECTION. THE SET POINTS (X0; ξ0 ) OF THE COTANGENT BUNDLE T*X WHERE A SHEAF DOES NOT PROPAGATE IS CALLED ITS MICRO-SUPPORT.