  In BV formalism we can consider a Lagrangian submanifold as a gauge
condition. Starting with the BV action functional we construct a closed form on
the space of Lagrangian submanifolds. If the action functional is invariant
with respect to some group $H$ and $\Lambda$ is an $H$-invariant family of
Lagrangian submanifold then under certain conditions we construct a form on
$\Lambda$ that descends to a closed form on $\Lambda/H.$ Integrating the latter
form over a cycle in $\Lambda/H$ we obtain numbers that can have interesting
physical meaning. We show that one can get string amplitudes this way. Applying
this construction to topological quantum field theories one obtains topological
invariants.
