Letter to the editor by James Largay, includes “… The article states that PSERS — the teachers’ retirement plan — has unfunded obligations exceeding $40 billion; this amount is much smaller than the true liability. Pensions are rigid formula-driven promises to make future payments. Public sector pension promises in Pennsylvania are inviolate and virtually risk-free. They should be discounted to the present at a risk-free rate of, say, 2%, not the typical risk-adjusted rate of, say, 8%.”