RDP 9701: Inflation Regimes and Inflation Expectations Equation (12)

f_{t + 1, π_{t + 2}} (x) = \frac{\int_{- \infty}^{\infty} f_{η} (x - ε) f_{ε} (ε) f_{ε} (π_{t + 1} - x + ε) d ε}{\int_{- \infty}^{\infty} \int_{- \infty}^{\infty} f_{η} (y - ε) f_{ε} (ε) f ε (π_{t + 1} - y + ε) d ε d y,}