Let A1← A2← A3←⋯
be an inverse system of Banach-algebra homomorphisms, and let f be an
element of the limit algebra A. Suppose f is the limit of squares, that is,
f1↤f2↤f3↤⋯↤f,
where each fn has a square root in its algebra An. Does this require that f have a
square root in A? Our object is to show that the answer to this as well as some
similarly natural questions is ‘no’.