Though the mathematically inclined should also know that we're not looking at dp/dt, we're looking at p(t) - p(t-T). The difference is important, especially be

Though the mathematically inclined should also know that we're not looking at dp/dt, we're looking at p(t) - p(t-T). The difference is important, especially because we're looking at a yearly increase every month. The derivative of the annual inflation is not d^2p/dt^2 but (dp(t)/dt - dp(t-T)/dt).