Dilute instanton gas as the precursor to the integral quantum Hall effect

An explicit expression is proposed for the renormalization-group equations for σₓₓ, σxy, i.e., the magnetoconductance tensor for the two-dimensional disordered electronic system subject to a magnetic background field. The formulas are derived from the ``dilute instanton gas'' approximation, which is given a clear meaning within the previously derived nonlinear {σ}-model description for the transport properties of the system.