---

• n  an open curve formed by a plane that cuts the base of a right circular cone

• The curve miscalled "parabola" by PTI was neither parabola nor hyperbola, but an "exponential decay curve" which does approach, never reaches, its asymptote.
• If you plot the curve of these changing discount rates over time, you get something that looks like a hyperbola, hence that extremely catchy phrase "hyperbolic discounting.