 
Summary: Fields Institute Communications
Volume 00, 0000
Topological Problems in Wave Propagation Theory and
Topological Economy Principle in Algebraic Geometry
V. I. Arnold
Steklov Mathematical Institute,
Gubkina st. 8, Moscow, 117966, Russia
and
CEREMADE, Universit'e Paris 9  Dauphine
75775 Paris, Cedex 16e, France
Abstract. This is the third of the series of three lectures given by
Vladimir Arnold in June 1997 at the meeting in the Fields Institute
dedicated to his 60th birthday.
From the most skillful definition, free as it might be of
any inner contradictions, one can never deduce a new
fact.
M. Planck. Thermodynamics.
I wish to explain one general principle. In some cases it leads to theorems and
I shall also discuss these theorems. But in my opinion the principle itself, which is
not rigorously formulated, is more important because it contains more possibilities.
