Two-dimensional field reduction of the general theory of relativity

In the framework of general relativity theory, we consider a space–time whose metric depends on only one coordinate and time. We choose a gauge class such that all the constraint conditions of the theory of gravity as a gauge theory are explicitly solved and construct a Hamiltonian depending only on dynamical physical variables $($gravitons$)$. We show that such a Hamiltonian can be obtained from the Polyakov action for a string in an anti-de Sitter background space with a "string constant" depending on time.