A double pendulum is a pendulum with another pendulum attached to its end, and is a simple physical system[?] that exhibits rich dynamic behavior[?]. The double pendulum is governed by very complicated formulas that can be found here (http://scienceworld.wolfram.com/physics/DoublePendulum). The double pendulum relates to:
... members pursued various solo projects, most notably Bob Weir[?]'s Ratdog[?] and Phil Lesh and Friends[?]. The surviving members of the Dead fully reunited in mid-2002 as ...