  We investigate the question: for which functions
$f(x_1,...,x_n),~g(x_1,...,x_n)$ the asymptotic expansion of the integral $\int
g(x_1,...,x_n) e^{\frac{f(x_1,...,x_n)+x_1y_1+...+x_ny_n}{\hbar}}dx_1...dx_n$
consists only of the first term. We reveal a hidden projective invariance of
the problem which establishes its relation with geometry of projective
hypersurfaces of the form $\{(1:x_1:...:x_n:f)\}$. We also construct various
examples, in particular we prove that Kummer surface in $\mathbb{P}^3$ gives a
solution to our problem.
